ICSE – Grade 8 – Physics – Ch 08 – QA

Questions & Answers

ICSE - Grade - 8

Subject: Physics

Chapter - 08 - Current Electricity

Types of Questions

MCQ

  1. What is the mains voltage supplied to households in India?
    a) 110 V
    b) 220 V
     c) 330 V
     d) 440 V
     Answer: b

 

  1. The frequency of a.c. supply in India is:
    a) 25 Hz
    b) 50 Hz
     c) 60 Hz
     d) 100 Hz
     Answer: b

 

  1. The commercial unit of electrical energy is:
    a) Joule
    b) Watt
     c) Kilowatt-hour
     d) Ampere
     Answer: c

 

  1. Power consumed in a circuit is given by:
    a) P = VI
    b) P = I²R
     c) P = V²/R
     d) All of these
     Answer: d

 

  1. Electrical energy consumed is given by:
    a) W = V/I
    b) W = P × t
     c) W = I/V
     d) W = P/I
     Answer: b

 

  1. Which wire is always connected to the earth pin of a plug?
    a) Live
    b) Neutral
     c) Earth
     d) None
     Answer: c

 

  1. The live wire is colour-coded as:
    a) Red
    b) Black
     c) Green
     d) Blue
     Answer: a

 

  1. The neutral wire is colour-coded as:
    a) Red
    b) Black
     c) Green
     d) Yellow
     Answer: b

 

  1. The earth wire is colour-coded as:
    a) Red
    b) Blue
     c) Green
     d) Black
     Answer: c

 

  1. Fuse is always connected in which wire?
    a) Neutral
    b) Earth
     c) Live
     d) Both Live & Neutral
     Answer: c

 

  1. What is the main purpose of a fuse?
    a) Increase voltage
    b) Reduce current
     c) Protect circuit from excess current
     d) Store energy
     Answer: c

 

  1. Which device can be reset after tripping due to excess current?
    a) Fuse
    b) MCB
     c) Electric meter
     d) Transformer
     Answer: b

 

  1. Household appliances are usually connected in:
    a) Series
    b) Parallel
     c) Both series and parallel
     d) None
     Answer: b

 

  1. The metal body of an appliance is connected to:
    a) Live wire
    b) Neutral wire
     c) Earth wire
     d) None
     Answer: c

 

  1. Two bulbs in series glow:
    a) Brighter than in parallel
    b) Dimmer than in parallel
     c) Same as in parallel
     d) Not at all
     Answer: b

 

  1. Two bulbs in parallel glow:
    a) Dimmer than in series
    b) Brighter than in series
     c) Same as in series
     d) Not at all
     Answer: b

 

  1. If one bulb fuses in a series connection:
    a) Other bulb glows brighter
    b) Other bulb glows dimmer
     c) Other bulb goes off
     d) No effect
     Answer: c

 

  1. If one bulb fuses in a parallel connection:
    a) Other bulb goes off
    b) Other bulb glows normally
     c) Other bulb glows brighter
     d) None
     Answer: b

 

  1. Power rating of an appliance is given on:
    a) Fuse
    b) Nameplate
     c) Wire
     d) Switch
     Answer: b

 

  1. Current drawn by an appliance is calculated as:
    a) I = P/V
    b) I = V/P
     c) I = V × P
     d) I = P × V
     Answer: a

 

  1. Which of the following is a conductor?
    a) Rubber
    b) Copper
     c) Glass
     d) Wood
     Answer: b

 

  1. Which of the following is an insulator?
    a) Aluminum
    b) Copper
     c) Rubber
     d) Iron
     Answer: c

 

  1. Electric charge can neither be created nor destroyed. This is:
    a) Ohm’s Law
    b) Conservation of charge
     c) Coulomb’s Law
     d) Faraday’s Law
     Answer: b

 

  1. Charging by rubbing is called:
    a) Conduction
    b) Induction
     c) Friction
     d) Polarisation
     Answer: c

 

  1. A glass rod rubbed with silk becomes:
    a) Positively charged
    b) Negatively charged
     c) Neutral
     d) Cannot tell
     Answer: a

 

  1. An ebonite rod rubbed with fur becomes:
    a) Positively charged
    b) Negatively charged
     c) Neutral
     d) Cannot tell
     Answer: b

 

  1. Charging a conductor by touching a charged body is:
    a) Conduction
    b) Induction
     c) Friction
     d) Polarisation
     Answer: a

 

  1. Charging a conductor without contact is called:
    a) Conduction
    b) Induction
     c) Friction
     d) Electrolysis
     Answer: b

 

  1. In induction, the conductor finally gets:
    a) Same charge as the inducing body
    b) Opposite charge
     c) No charge
     d) Random charge
     Answer: b

 

  1. Which electroscope has two thin leaves that diverge on charging?
    a) Pith ball
    b) Gold leaf
     c) Metal rod
     d) Simple switch
     Answer: b

 

  1. Pith ball electroscope works on:
    a) Induction only
    b) Repulsion between like charges
     c) Attraction of unlike charges
     d) Conduction only
     Answer: b

 

  1. Lightning is a discharge of:
    a) Static electricity
    b) Current electricity
     c) Magnetic field
     d) Heat energy
     Answer: a

 

  1. Franklin’s kite experiment proved:
    a) Current electricity flows in water
    b) Lightning is electrical
     c) MCB works automatically
     d) Fuse melts on overload
     Answer: b

 

  1. A lightning conductor protects a building by:
    a) Increasing voltage
    b) Providing safe path to earth
     c) Storing charge
     d) Changing current to AC
     Answer: b

 

  1. Earth wire is connected to:
    a) Metal plate buried in moist soil
    b) Ceiling fan
     c) Live wire
     d) Switchboard
     Answer: a

 

  1. Two bulbs connected in opposition across cells:
    a) Glow brighter
    b) Glow dimmer or not at all
     c) Glow normally
     d) Fuse blows
     Answer: b

 

  1. Fuse rating is chosen slightly:
    a) Below normal current
    b) Equal to normal current
     c) Above normal current
     d) Very high
     Answer: c

 

  1. Current drawn by 1000 W, 220 V heater:
    a) 4.5 A
    b) 5 A
     c) 6 A
     d) 10 A
     Answer: b

 

  1. 1 kWh = ?
    a) 360 J
    b) 3.6 × 10³ J
     c) 3.6 × 10⁶ J
     d) 3600 W
     Answer: c

 

  1. Appliances are connected in parallel so that:
    a) Each appliance gets full voltage
    b) Current divides equally
     c) If one goes off, others remain on
     d) All of these
     Answer: d

 

  1. Main switch in a house controls:
    a) Entire house supply
    b) Individual bulb
     c) Fuse rating
     d) Earthing
     Answer: a

 

  1. Distribution board contains:
    a) Main fuse
    b) MCBs or fuses for sub-circuits
     c) Meter
     d) Transformer
     Answer: b

 

  1. Short-circuit occurs due to:
    a) Overloading
    b) Broken wire
     c) Direct contact between live and neutral
     d) Fuse
     Answer: c

 

  1. Overloading can cause:
    a) Shock
    b) Heating/fire
     c) Reduced voltage
     d) None
     Answer: b

 

  1. Precaution while using electricity:
    a) Use wet hands
    b) Overload sockets
     c) Correct fuse & earthing
     d) Ignore insulation damage
     Answer: c

 

  1. Two bulbs in series, voltage across each is:
    a) Equal to supply voltage
    b) Divided according to resistance
     c) Zero
     d) Same as parallel
     Answer: b

 

  1. Two bulbs in parallel, voltage across each is:
    a) Equal to supply voltage
    b) Divided
     c) Zero
     d) Depends on current
     Answer: a

 

  1. MCB works on:
    a) Thermal or magnetic effect
    b) Chemical reaction
     c) Resistance
     d) Capacitance
     Answer: a

 

  1. Lightning conductor should be:
    a) Short and thin
    b) Tall with sharp spikes
     c) Flat plate
     d) Plastic rod
     Answer: b

 

  1. In static electricity, charges at rest:
    a) Flow freely
    b) Are stationary but exert force
     c) Always negative
     d) Conduct heat
     Answer: b

Fill in the Blanks

  1. The mains voltage supplied to households in India is __________.
    220 V

 

  1. The frequency of a.c. supply in India is __________.
    50 Hz

 

  1. The commercial unit of electrical energy is __________.
    Kilowatt-hour (kWh)

 

  1. Power consumed in a circuit is given by the formula __________.
    P = VI

 

  1. Electrical energy consumed is calculated by __________.
    W = P × t
  2. The live wire is colour-coded __________.


 Red

 

  1. The neutral wire is colour-coded __________.
    Black

 

  1. The earth wire is colour-coded __________.
    Green

 

  1. A fuse is always connected in the __________ wire.
    Live

 

  1. The main purpose of a fuse is to __________.
    Protect the circuit from excess current

 

  1. A device that can be reset after tripping due to excess current is called __________.
    MCB

 

  1. Household appliances are usually connected in __________.
    Parallel

 

  1. The metal body of an appliance is connected to the __________ wire.
    Earth

 

  1. Two bulbs connected in series glow __________ than in parallel.
    Dimmer

 

  1. Two bulbs connected in parallel glow __________ than in series.
    Brighter

 

  1. If one bulb fuses in a series connection, the other bulb __________.
    Goes off

 

  1. If one bulb fuses in a parallel connection, the other bulb __________.
    Glows normally

 

  1. The power rating of an appliance is given on its __________.
    Nameplate

 

  1. Current drawn by an appliance is calculated using the formula __________.
    I = P/V

 

  1. A glass rod rubbed with silk becomes __________ charged.
    Positively

 

  1. An ebonite rod rubbed with fur becomes __________ charged.
    Negatively

 

  1. Electric charge can neither be created nor destroyed. This is the law of __________.
    Conservation of charge

 

  1. Charging a conductor by touching it with a charged body is called __________.
    Conduction

 

  1. Charging a conductor without contact is called __________.
    Induction

 

  1. Conductors allow __________ of electric charges.
    Flow

 

  1. Insulators do not allow __________ of electric charges.
    Flow

 

  1. The instrument used to detect electric charges is called __________.
    Electroscope

 

  1. The type of electroscope with thin metal leaves is called __________.
    Gold leaf electroscope

 

  1. The type of electroscope with small balls is called __________.
    Pith ball electroscope

 

  1. Lightning is a discharge of __________ electricity.
    Static

 

  1. Benjamin Franklin proved that lightning is __________.
    Electrical

 

  1. A __________ provides a safe path for lightning to the earth.
    Lightning conductor

 

  1. The current in a household is alternating in nature and is called __________.
    AC (Alternating Current)

 

  1. The main switch in a house controls the __________ supply.
    Entire house

 

  1. The distribution board contains __________ for sub-circuits.
    MCBs or fuses

 

  1. Short-circuit occurs due to direct contact between __________ and __________ wires.
    Live, Neutral

 

  1. Overloading in a circuit can cause __________ or __________.
    Heating, Fire

 

  1. Electrical energy is measured in __________.
    Kilowatt-hour (kWh)

 

  1. 1 kWh is equal to __________ joules.
    3.6 × 10⁶

 

  1. Appliances are connected in parallel so that each gets the __________ voltage.
    Full

 

  1. Earthing prevents __________ from electric shocks.
    Accidents / Electric shocks

 

  1. A fuse has a __________ melting point.
    Low

 

  1. The fuse melts when current exceeds the __________.
    Rated value / Maximum limit

 

  1. Two bulbs in series share the __________ according to their resistance.
    Voltage

 

  1. Two bulbs in parallel receive the __________ supply voltage.
    Full

 

  1. A lightning conductor should be __________ and __________.
    Tall, pointed

 

  1. Static charges at rest __________ forces on each other.
    Exert

 

  1. Like charges __________ each other.
    Repel

 

  1. Unlike charges __________ each other.
    Attract

 

  1. A conductor connected to the earth to prevent electric shocks is called __________.
    Earthing

Name the Following

  1. Name the commercial unit of electrical energy.
    Kilowatt-hour (kWh)

 

  1. Name the device used to protect a circuit from excess current.
    Fuse

 

  1. Name the device that can be reset after tripping due to excess current.
    MCB (Miniature Circuit Breaker)

 

  1. Name the wire that is colour-coded red in a household circuit.
    Live wire

 

  1. Name the wire that is colour-coded black in a household circuit.
    Neutral wire

 

  1. Name the wire that is colour-coded green in a household circuit.
    Earth wire

 

  1. Name the law which states that electric charge can neither be created nor destroyed.
    Law of Conservation of Charge

 

  1. Name the process of charging a conductor by touching it with a charged body.
    Conduction

 

  1. Name the process of charging a conductor without contact.
    Induction

 

  1. Name the instrument used to detect electric charges.
    Electroscope

 

  1. Name the type of electroscope which has thin metal leaves.
    Gold leaf electroscope

 

  1. Name the type of electroscope which has small balls suspended on threads.
    Pith ball electroscope

 

  1. Name the type of current supplied to households.
    Alternating Current (AC)

 

  1. Name the type of current in which electrons flow in one direction only.
    Direct Current (DC)

 

  1. Name the safety device connected to the earth wire of an appliance.
    Earthing

 

  1. Name the person who proved that lightning is electrical.
    Benjamin Franklin

 

  1. Name the device used to protect a building from lightning.
    Lightning conductor

 

  1. Name the main device that controls the electricity supply to a house.
    Main switch

 

  1. Name the board that contains MCBs or fuses for sub-circuits.
    Distribution board

 

  1. Name the condition in which live and neutral wires come in direct contact.
    Short-circuit

 

  1. Name the effect caused by excessive current due to overloading.
    Heating / Fire

 

  1. Name the type of connection in which all appliances receive full voltage.
    Parallel connection

 

  1. Name the type of connection in which appliances share voltage.
    Series connection

 

  1. Name the instrument used to measure household electricity consumption.
    Electric meter

 

  1. Name the metal rod rubbed with silk which becomes positively charged.
    Glass rod

 

  1. Name the rod rubbed with fur which becomes negatively charged.
    Ebonite rod

 

  1. Name the phenomenon where like charges repel and unlike charges attract.
    Electrostatic force

 

  1. Name the unit of power in electricity.

 Watt (W)

 

  1. Name the formula to calculate power in an electrical circuit.
    P = VI

 

  1. Name the formula to calculate electrical energy consumed.
    W = P × t

 

  1. Name the wire connected to the earth pin of a plug.
    Earth wire

 

  1. Name the wire connected to the fuse in a household circuit.
    Live wire

 

  1. Name the type of current in a cell.
    Direct Current (DC)

 

  1. Name the safety device that melts on excess current.
    Fuse

 

  1. Name the device that provides a safe path for lightning to the earth.
    Lightning conductor

 

  1. Name the type of electricity produced when a rod is rubbed with a cloth.
    Static electricity

 

  1. Name the two types of charges in electricity.
    Positive and Negative

 

  1. Name the type of connection used in series experiment with two bulbs.
    Series connection

 

  1. Name the type of connection used in parallel experiment with two bulbs.
    Parallel connection

 

  1. Name the point where electricity enters a house from the main supply.
    Distribution board

 

  1. Name the appliance rating label that mentions voltage, current, and power.
    Nameplate

 

  1. Name the condition when current in a circuit exceeds the safe limit.
    Overload

 

  1. Name the device that divides supply to various sub-circuits.
    Distribution board

 

  1. Name the process of charging by rubbing.
    Friction

 

  1. Name the law that states like charges repel and unlike charges attract.
    Coulomb’s law (Electrostatic Law)

 

  1. Name the metal plate buried in moist soil to prevent shocks.
    Earthing plate

 

  1. Name the electrical quantity measured by an electric meter.
    Electrical energy

 

  1. Name the type of switch that automatically trips under overload.
    MCB (Miniature Circuit Breaker)

 

  1. Name the condition where appliances are damaged due to sudden high current.
    Short-circuit / Overload

 

  1. Name the device used to safely disconnect electricity from the entire house.
    Main switch

Answer in One Word

  1. The wire that carries current to an appliance is called:
    Live

 

  1. The wire that completes the circuit back to the supply is called:
    Neutral

 

  1. The wire used for safety is called:
    Earth

 

  1. The device that protects a circuit from excess current is called:
    Fuse

 

  1. The device that can be reset after tripping is called:
    MCB

 

  1. The unit of electrical energy is:
    Kilowatt-hour

 

  1. The unit of electric power is:
    Watt

 

  1. Current in which electrons flow in one direction is called:
    DC

 

  1. Current in which electrons alternate direction is called:
    AC

 

  1. The instrument used to measure electricity consumption is:
    Electric meter

 

  1. A rod that becomes positively charged when rubbed with silk is:
    Glass

 

  1. A rod that becomes negatively charged when rubbed with fur is:
    Ebonite

 

  1. Charges that repel each other are:
    Like

 

  1. Charges that attract each other are:
    Unlike

 

  1. The law stating charge is neither created nor destroyed is:
    Conservation

 

  1. Charging by rubbing is called:
    Friction
  2. Charging by contact is called:


 Conduction

 

  1. Charging without contact is called:
    Induction

 

  1. Device to detect electric charges is:
    Electroscope

 

  1. Type of electroscope with thin metal leaves is:
    Gold leaf

 

  1. Type of electroscope with small balls is:
    Pith ball

 

  1. Lightning is a form of:
    Static

 

  1. Device used to protect buildings from lightning is:
    Conductor

 

  1. Connection where all appliances get full voltage is:
    Parallel

 

  1. Connection where appliances share voltage is:
    Series

 

  1. The main device controlling electricity in a house is:
    Main switch

 

  1. Board containing MCBs and fuses is called:
    Distribution board

 

  1. Sudden contact between live and neutral wires is:
    Short-circuit

 

  1. Excess current causing heating/fire is called:
    Overload

 

  1. The plate connected to earth for safety is:
    Earthing

 

  1. Energy consumed = Power ×:
    Time

 

  1. Power consumed = Voltage ×:
    Current

 

  1. Household supply voltage in India is:
    220 V

 

  1. Household supply frequency in India is:
    50 Hz

 

  1. A fuse melts because it has a low:
    Melting point

 

  1. MCB works on thermal or:
    Magnetic

 

  1. Two bulbs in series share:
    Voltage

 

  1. Two bulbs in parallel receive:
    Voltage

 

  1. Instrument showing energy consumption in numbers is:
    Meter

 

  1. Protective device that blows under overload is:
    Fuse

 

  1. Protective device that trips and can be reset is:
    MCB

 

  1. Rubbing a rod to produce charge is called:
    Friction

 

  1. Positive charge is usually carried by a:
    Proton

 

  1. Negative charge is usually carried by an:
    Electron

 

  1. Lightning conductor is usually made of:
    Copper

 

  1. Conductor connected to the earth is called:
    Earthing

 

  1. Electric charge at rest is called:
    Static

 

  1. Law stating like charges repel is:
    Coulomb

 

  1. Appliance rating showing voltage and power is:
    Nameplate

 

  1. Electrical phenomenon demonstrated by Benjamin Franklin’s kite experiment is:
    Lightning

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Find the Odd Man Out

  1. Copper, Aluminum, Rubber, Iron
    Answer: Rubber – It is an insulator, others are conductors.

 

  1. Live wire, Neutral wire, Earth wire, Fuse
    Answer: Fuse – It is a device, others are wires.

 

  1. MCB, Fuse, Electric meter, Lightning conductor
    Answer: Electric meter – It measures energy, others protect circuits.

 

  1. Glass rod, Ebonite rod, Copper rod, Silk cloth
    Answer: Silk cloth – It is a non-conductor and used for rubbing, others are rods.

 

  1. Positive charge, Negative charge, Neutral, Current
    Answer: Current – It flows, others are types of charges.

 

  1. Pith ball, Gold leaf, Electroscope, Fuse
    Answer: Fuse – It is a safety device, others detect charge.

 

  1. Series connection, Parallel connection, Fuse, Short-circuit
    Answer: Fuse – It is a safety device, others are types of connections or faults.

 

  1. Conduction, Induction, Friction, Lightning conductor
    Answer: Lightning conductor – It protects buildings, others are charging methods.

 

  1. AC, DC, Voltage, Current
    Answer: Voltage – It is potential difference, others are types of current or quantity.

 

  1. Earth, Live, Neutral, Meter
    Answer: Meter – It measures energy, others are wires.

 

  1. Overload, Short-circuit, Fuse, Insulator
    Answer: Insulator – It is a material, others are electrical conditions/devices.

 

  1. Copper, Aluminum, Rubber, Iron
    Answer: Rubber – Non-conductor, others are metals.

 

  1. Glass, Ebonite, Rubber, Copper
    Answer: Copper – It is a conductor, others are insulators.

 

  1. Series, Parallel, Conductor, Resistance
    Answer: Resistance – It is a property, others are types of circuit connections.

 

  1. Positive, Negative, Neutral, Current
    Answer: Current – It is the flow of charge, others are types of charges.

 

  1. Fuse, MCB, Lightning conductor, Copper wire
    Answer: Copper wire – It is a conductor, others are protective devices.

 

  1. Electroscope, Pith ball, Gold leaf, Fuse
    Answer: Fuse – Safety device, others detect charges.

 

  1. AC, DC, Static, Meter
    Answer: Meter – Measures energy, others are types of electricity.

 

  1. Lightning, Current, Conduction, Induction
    Answer: Lightning – It is a natural phenomenon, others are processes.

 

  1. Live, Neutral, Earth, Meter
    Answer: Meter – It measures, others are wires.

 

  1. Aluminum, Copper, Gold, Rubber
    Answer: Rubber – Non-conductor, others are metals.

 

  1. Glass, Ebonite, Wood, Iron
    Answer: Iron – Conductor, others are insulators.

 

  1. Friction, Conduction, Induction, MCB
    Answer: MCB – Protective device, others are charging methods.

 

  1. Positive, Negative, Neutral, Earth
    Answer: Earth – It is a wire, others are charges.

 

  1. Fuse, MCB, Meter, Conductor
    Answer: Conductor – Material, others are devices.

 

  1. Short-circuit, Overload, Resistance, Series
    Answer: Resistance – Property, others are circuit conditions or types.

 

  1. AC, DC, Static, Fuse
    Answer: Fuse – Device, others are types of electricity.

 

  1. Live, Neutral, Copper, Earth
    Answer: Copper – Material, others are wires.

 

  1. Glass, Ebonite, Rubber, Aluminum
    Answer: Aluminum – Conductor, others are insulators.

 

  1. Positive, Negative, Neutral, Current
    Answer: Current – It is moving charge, others are types of charge.

 

  1. Series, Parallel, Fuse, Lightning conductor
    Answer: Fuse – Safety device, others are connection types or protective devices for lightning.

 

  1. Pith ball, Gold leaf, Electroscope, MCB
    Answer: MCB – Safety device, others detect charges.

 

  1. Electric meter, Fuse, MCB, Lightning conductor
    Answer: Electric meter – Measures energy, others protect circuits.

 

  1. Live, Neutral, Earth, Battery
    Answer: Battery – Source of electricity, others are wires.

 

  1. AC, DC, Static, Copper
    Answer: Copper – Material, others are types of electricity.

 

  1. Overload, Short-circuit, Fuse, Insulator
    Answer: Insulator – Material, others are electrical conditions or devices.

 

  1. Glass rod, Ebonite rod, Copper rod, Fuse
    Answer: Fuse – Device, others are rods used in experiments.

 

  1. Positive, Negative, Neutral, Lightning
    Answer: Lightning – Natural phenomenon, others are charges.

 

  1. Friction, Conduction, Induction, Earth wire
    Answer: Earth wire – Wire, others are charging methods.

 

  1. Main switch, MCB, Fuse, Copper wire
    Answer: Copper wire – Conductor, others are devices controlling electricity.

 

  1. Meter, Fuse, MCB, Lightning conductor
    Answer: Meter – Measures energy, others protect circuits.

 

  1. AC, DC, Voltage, Current
    Answer: Voltage – Potential difference, others are currents.

 

  1. Live, Neutral, Earth, MCB
    Answer: MCB – Device, others are wires.

 

  1. Aluminum, Copper, Gold, Glass
    Answer: Glass – Insulator, others are metals.

 

  1. Series, Parallel, Resistance, Conduction
    Answer: Conduction – Property/process, others are types of connection or resistance.

 

  1. Lightning, Current, AC, DC
    Answer: Lightning – Natural, others are types of electricity.

 

  1. Fuse, MCB, Meter, Pith ball
    Answer: Pith ball – Detects charge, others protect or measure.

 

  1. Positive, Negative, Neutral, Copper
    Answer: Copper – Material, others are charges.

 

  1. Friction, Conduction, Induction, Lightning
    Answer: Lightning – Natural, others are charging methods.

 

  1. Earth wire, Live wire, Neutral wire, Static electricity
    Answer: Static electricity – Phenomenon, others are wires.

Match the Pair

Set 1

Column A:

  1. Live wire
  2. Neutral wire
  3. Earth wire
  4. Fuse
  5. MCB

Column B (shuffled):
 a) Protects circuit from overcurrent and can be reset
 b) Carries current to appliance
 c) Completes circuit back to supply
 d) Safety wire connected to metal body
 e) Safety device that melts under excess current

Answer:
 1 – b
 2 – c
 3 – d
 4 – e
 5 – a



Set 2

Column A:

  1. Series connection
  2. Parallel connection
  3. Power (P)
  4. Electrical energy (W)
  5. Electric meter

Column B (shuffled):
 a) Measures energy consumed in units
 b) Energy consumed = Power × Time
 c) Voltage is shared among devices
 d) Power = Voltage × Current
 e) Each appliance gets full supply voltage

Answer:
 1 – c
 2 – e
 3 – d
 4 – b
 5 – a



Set 3

Column A:

  1. Static electricity
  2. Conduction
  3. Induction
  4. Friction
  5. Electroscope

Column B (shuffled):
 a) Charging a conductor without contact
 b) Detects electric charges
 c) Electric charge at rest
 d) Charging by rubbing
 e) Charging by direct contact

Answer:
 1 – c
 2 – e
 3 – a
 4 – d
 5 – b



Set 4

Column A:

  1. Pith ball electroscope
  2. Gold leaf electroscope
  3. Positive charge
  4. Negative charge
  5. Neutral

Column B (shuffled):
 a) Small suspended balls that diverge when charged
 b) Type of charge carried by protons
 c) Leaves diverge when charged
 d) Type of charge carried by electrons
 e) No net charge

Answer:
 1 – a
 2 – c
 3 – b
 4 – d
 5 – e



Set 5

Column A:

  1. Lightning
  2. Lightning conductor
  3. Benjamin Franklin
  4. Earthing
  5. Overload

Column B (shuffled):
 a) Protects building from lightning
 b) Sudden discharge of static electricity
 c) Provides a safe path for excess current to ground
 d) Scientist who proved lightning is electrical
 e) Excess current causing heating/fire

Answer:
 1 – b
 2 – a
 3 – d
 4 – c
 5 – e



Set 6

Column A:

  1. AC
  2. DC
  3. Household voltage in India
  4. Household frequency in India
  5. Electric shock prevention

Column B (shuffled):
 a) Alternating current
 b) Direct current
 c) 220 V
 d) 50 Hz
 e) Earthing

Answer:
 1 – a
 2 – b
 3 – c
 4 – d
 5 – e



Set 7

Column A:

  1. Fuse rating
  2. Series bulb experiment
  3. Parallel bulb experiment
  4. Nameplate
  5. Main switch

Column B (shuffled):
 a) Indicates voltage, current, power of appliance
 b) Slightly above normal current
 c) Controls electricity for whole house
 d) Each bulb receives full voltage
 e) Voltage is shared among bulbs

Answer:
 1 – b
 2 – e
 3 – d
 4 – a
 5 – c



Set 8

Column A:

  1. Copper
  2. Aluminum
  3. Rubber
  4. Glass
  5. Iron

Column B (shuffled):
 a) Conductor
 b) Insulator
 c) Conductor
 d) Insulator
 e) Conductor

Answer:
 1 – a
 2 – c
 3 – b
 4 – d
 5 – e



Set 9

Column A:

  1. Current (I)
  2. Voltage (V)
  3. Power (P)
  4. Energy (W)
  5. Time (t)

Column B (shuffled):
 a) P = VI
 b) W = P × t
 c) Flow of charge
 d) Potential difference
 e) Duration of electricity flow

Answer:
 1 – c
 2 – d
 3 – a
 4 – b
 5 – e



Set 10

Column A:

  1. Short-circuit
  2. Overload
  3. Insulator
  4. Conductor
  5. Electrostatic force

Column B (shuffled):
 a) Allows flow of electrons
 b) Excess current causing heating/fire
 c) Sudden contact between live and neutral wires
 d) Material that does not allow flow of electrons
 e) Like charges repel, unlike charges attract

Answer:
 1 – c
 2 – b
 3 – d
 4 – a
 5 – e

Short Answer Questions  

  1. What is the function of the live wire?
    Answer: It carries current from the supply to the appliance.

 

  1. What is the function of the neutral wire?
    Answer: It completes the electric circuit by carrying current back to the supply.

 

  1. What is the function of the earth wire?
    Answer: It provides a safe path for excess current to prevent electric shocks.

 

  1. What is a fuse?
    Answer: A fuse is a safety device that melts when current exceeds a safe limit.

 

  1. What is an MCB?
    Answer: MCB is a miniature circuit breaker that trips when current exceeds the safe limit and can be reset.

 

  1. Why are household appliances connected in parallel?
    Answer: So that each appliance receives the full supply voltage.

 

  1. Why is earthing important for metallic appliances?
    Answer: It prevents electric shocks by directing excess current to the ground.

 

  1. Define static electricity.
    Answer: Static electricity is electric charge at rest on a body.

 

  1. What is the use of an electroscope?
    Answer: An electroscope is used to detect electric charges.

 

  1. What is the difference between pith ball and gold leaf electroscopes?
    Answer: Pith ball shows movement of a ball, whereas gold leaf diverges when charged.

 

  1. What is the principle of a lightning conductor?
    Answer: It provides a low resistance path to earth for lightning discharge.

 

  1. What is the household supply voltage in India?
    Answer: 220 volts.

 

  1. What is the household supply frequency in India?
    Answer: 50 Hz.

 

  1. What is the relationship between energy, power, and time?
    Answer: Electrical energy consumed = Power × Time.

 

  1. How is electric power calculated?
    Answer: Power = Voltage × Current.

 

  1. What happens to bulbs in series if one bulb blows out?
    Answer: All bulbs in the series go out.

 

  1. What happens to bulbs in parallel if one bulb blows out?
    Answer: Other bulbs continue to glow.

 

  1. What is overloading?
    Answer: Overloading is drawing excessive current in a circuit.

 

  1. What is a short-circuit?
    Answer: A short-circuit occurs when live and neutral wires touch directly.

 

  1. What is the colour code of the live wire in India?
    Answer: Red.

 

  1. What is the colour code of the neutral wire in India?
    Answer: Black.

 

  1. What is the colour code of the earth wire in India?
    Answer: Green or green-yellow.

 

  1. Name a good conductor of electricity.
    Answer: Copper.

 

  1. Name a good insulator.
    Answer: Rubber.

 

  1. What is conduction?
    Answer: Charging a conductor by direct contact.

 

  1. What is induction?
    Answer: Charging a conductor without direct contact.

 

  1. What is friction method of charging?
    Answer: Charging a body by rubbing two materials together.

 

  1. What type of charge does a glass rod acquire when rubbed with silk?
    Answer: Positive charge.

 

  1. What type of charge does an ebonite rod acquire when rubbed with fur?
    Answer: Negative charge.

 

  1. State the law of conservation of charge.
    Answer: Electric charge can neither be created nor destroyed.

 

  1. What is the function of an electric meter?
    Answer: To measure the electrical energy consumed in units.

 

  1. Define unit of electrical energy.
    Answer: One unit is the energy consumed when a device of one kilowatt works for one hour.

 

  1. What is a household main switch?
    Answer: It controls electricity supply to the entire house.

 

  1. What is the purpose of a distribution board?
    Answer: To divide electricity supply into sub-circuits for protection and control.

 

  1. What is lightning?
    Answer: Lightning is a sudden discharge of static electricity in the atmosphere.

 

  1. Who proved lightning is electrical?
    Answer: Benjamin Franklin.

 

  1. What is the function of a lightning conductor?
    Answer: To safely direct lightning discharge to the ground.

 

  1. Define electrical energy.
    Answer: Energy consumed by an appliance in producing work or heat.

 

  1. What happens when two like charges are brought near each other?
    Answer: They repel each other.

 

  1. What happens when two unlike charges are brought near each other?
    Answer: They attract each other.

 

  1. Why is copper used in wires?
    Answer: Because it is a good conductor with low resistance.

 

  1. Why are fuses rated slightly above the normal current?
    Answer: To allow normal current flow without blowing.

 

  1. Why do we use MCBs instead of fuses in modern circuits?
    Answer: Because MCBs can be reset and do not need replacement after tripping.

 

  1. What is the difference between series and parallel circuits?
    Answer: In series, current is the same; in parallel, voltage is the same across devices.

 

  1. What is the danger of a short-circuit?
    Answer: It can cause overheating or fire.

 

  1. Give one precaution while using electricity at home.
    Answer: Never touch appliances with wet hands.

 

  1. Give another precaution while using electricity.
    Answer: Ensure wires and appliances are properly insulated.

 

  1. What is the effect of overloading a socket?
    Answer: It may cause fuse to blow or MCB to trip.

 

  1. How does a gold leaf electroscope indicate charge?
    Answer: The leaves diverge due to repulsion of like charges.

 

  1. How can you demonstrate static electricity?
    Answer: By rubbing a rod with silk and attracting small pieces of paper.

Puzzles

  1. I carry current to your appliances, red is my dress. Who am I?
    Answer: Live wire

 

  1. I complete the circuit and am black in colour. Who am I?
    Answer: Neutral wire

 

  1. I protect you from electric shocks by going into the ground. Who am I?
    Answer: Earth wire

 

  1. I melt to save your house when too much current flows. Who am I?
    Answer: Fuse

 

  1. I trip automatically and can be reset, protecting your home. Who am I?
    Answer: MCB

 

  1. Two bulbs are in my path, and if one fails, the other still glows. What am I?
    Answer: Parallel circuit

 

  1. I am the energy consumed when a 1 kW appliance works for 1 hour. Who am I?
    Answer: Unit of electrical energy

 

  1. I show how much electricity you’ve used. Who am I?
    Answer: Electric meter

 

  1. I am a conductor that attracts lightning to the ground. What am I?
    Answer: Lightning conductor

 

  1. I am the sudden discharge of static electricity in clouds. What am I?
    Answer: Lightning

 

  1. Rub me with silk and I become positively charged. Who am I?
    Answer: Glass rod

 

  1. Rub me with fur and I become negatively charged. Who am I?
    Answer: Ebonite rod

 

  1. I am a device that detects electric charges with thin leaves. Who am I?
    Answer: Gold leaf electroscope

 

  1. I am a lightweight ball suspended on a thread to detect charges. Who am I?
    Answer: Pith ball electroscope

 

  1. I flow in one direction only, from positive to negative. What am I?
    Answer: Direct current (DC)

 

  1. I change direction periodically and power your home appliances. What am I?
    Answer: Alternating current (AC)

 

  1. I am the push that makes current flow. What am I?
    Answer: Voltage

 

  1. I am the flow of electric charge in a circuit. What am I?
    Answer: Current

 

  1. I provide a low-resistance path for lightning to reach the earth. Who am I?
    Answer: Lightning conductor

 

  1. I am transferred from one body to another when rubbed. What am I?
    Answer: Electrons

 

  1. I repel like charges and attract opposite charges. What am I?
    Answer: Electric charge

 

  1. I measure energy consumed in kilowatt-hours. What am I?
    Answer: Electric meter

 

  1. I divide electricity into safe sub-circuits in your home. Who am I?
    Answer: Distribution board

 

  1. I prevent electric shocks when connected to metallic appliances. What am I?
    Answer: Earth wire

 

  1. I am the wire that completes the circuit, usually black. Who am I?
    Answer: Neutral wire

 

  1. I protect against short-circuits and overloads by tripping. Who am I?
    Answer: MCB

 

  1. I carry current to appliances and am often red. Who am I?
    Answer: Live wire

 

  1. I am the law stating that charge cannot be created or destroyed. Who am I?
    Answer: Law of conservation of charge

 

  1. I attract small pieces of paper when rubbed with silk. Who am I?
    Answer: Charged rod

 

  1. I show divergence of leaves when a body is charged. Who am I?
    Answer: Gold leaf electroscope

 

  1. I am produced by rubbing two materials together. What am I?
    Answer: Static electricity

 

  1. I am a sudden current flow caused by touching live and neutral wires. What am I?
    Answer: Short-circuit

 

  1. I allow each appliance in a home to receive full voltage. What am I?
    Answer: Parallel connection

 

  1. I am generated at power stations and transmitted to your home. Who am I?
    Answer: Electrical energy

 

  1. I am a conductor used for household wiring. Who am I?
    Answer: Copper

 

  1. I am a poor conductor and used for insulation. Who am I?
    Answer: Rubber

 

  1. I divide electricity into manageable parts and prevent overload. Who am I?
    Answer: Distribution board

 

  1. I am a safety device that melts when current is too high. Who am I?
    Answer: Fuse

 

  1. I allow current to flow in one direction but not the other. Who am I?
    Answer: Diode (basic concept in electricity)

 

  1. I prevent accidents by providing a path for excess current to earth. Who am I?
    Answer: Earth wire

 

  1. I am used to detect charges without touching the body. Who am I?
    Answer: Electroscope

 

  1. I am energy consumed when a device of 1 kW runs for 1 hour. Who am I?
    Answer: Unit of electrical energy

 

  1. I am the wire colour-coded green-yellow for safety. Who am I?
    Answer: Earth wire

 

  1. I am the wire colour-coded red that carries current to appliances. Who am I?
    Answer: Live wire

 

  1. I am the electrical phenomenon observed in thunderstorms. Who am I?
    Answer: Lightning

 

  1. I am the metal rod that attracts lightning safely. Who am I?
    Answer: Lightning conductor

 

  1. I am the device that trips automatically in case of overload. Who am I?
    Answer: MCB

 

  1. I am the part of a circuit that allows independent operation of appliances. Who am I?
    Answer: Parallel branch

 

  1. I am the thin wire inside a fuse. Who am I?
    Answer: Fuse wire

 

  1. I am the flow of electrons from negative to positive. Who am I?
    Answer: Electric current

Difference Between:

  1. Difference between Live Wire and Neutral Wire
    Answer:
  • Live Wire: Carries current from the power source to the appliance; usually red in colour.
  • Neutral Wire: Completes the circuit by carrying current back to the supply; usually black in colour.

 

  1. Difference between Fuse and MCB
    Answer:
  • Fuse: A thin wire that melts when current exceeds the safe limit; needs replacement after blowing.
  • MCB: An automatic switch that trips on overcurrent; can be reset without replacement.

 

  1. Difference between Series Circuit and Parallel Circuit
    Answer:
  • Series Circuit: Current is the same through all components; voltage divides among components.
  • Parallel Circuit: Voltage is the same across each component; current divides among branches.

 

  1. Difference between AC and DC
    Answer:
  • AC (Alternating Current): Current changes direction periodically; used in household supply.
  • DC (Direct Current): Current flows in one direction only; used in batteries.

 

  1. Difference between Conductor and Insulator
    Answer:
  • Conductor: Material that allows current to pass easily, e.g., copper.
  • Insulator: Material that does not allow current to pass easily, e.g., rubber.

 

  1. Difference between Charging by Conduction and Charging by Induction
    Answer:
  • Conduction: Requires direct contact; the conductor acquires the same type of charge as the charged body.
  • Induction: No contact needed; opposite charges appear on different ends of the conductor.

 

  1. Difference between Pith Ball Electroscope and Gold Leaf Electroscope
    Answer:
  • Pith Ball Electroscope: Small lightweight ball that moves towards or away from charged body; simple and quick.
  • Gold Leaf Electroscope: Thin metal leaves diverge when charged; more sensitive and can detect small charges.

 

  1. Difference between Static Electricity and Current Electricity
    Answer:
  • Static Electricity: Electric charge at rest; does not flow.
  • Current Electricity: Flow of electric charges through a conductor; can do work.

 

  1. Difference between Earth Wire and Neutral Wire
    Answer:
  • Earth Wire: Provides safety path for leakage current to the ground; green/yellow colour.
  • Neutral Wire: Completes circuit for current to return to supply; black colour.

 

  1. Difference between Electric Meter and Electric Fuse
    Answer:
  • Electric Meter: Measures electrical energy consumed in units (kWh).
  • Electric Fuse: Protects appliances by breaking circuit when current exceeds safe limit.

 

  1. Difference between Live Wire and Earth Wire
    Answer:
  • Live Wire: Carries current to the appliance; red colour.
  • Earth Wire: Carries leakage current safely to the ground; green/yellow colour.

 

  1. Difference between Conductor Charging and Insulator Charging
    Answer:
  • Conductor Charging: Charge spreads uniformly over the surface; can conduct current.
  • Insulator Charging: Charge remains at the place where it is deposited; does not conduct current.

 

  1. Difference between Overload and Short Circuit
    Answer:
  • Overload: Too many appliances draw more current than the circuit can handle.
  • Short Circuit: Live and neutral wires touch directly, causing sudden flow of large current.

 

  1. Difference between Commercial Unit of Electricity and Electrical Energy
    Answer:
  • Commercial Unit: 1 kWh of electrical energy, used for billing.
  • Electrical Energy: Total energy consumed by an appliance, calculated as Power × Time.

 

  1. Difference between Frictional Charging and Induction Charging
    Answer:
  • Frictional Charging: Charge is transferred by rubbing two materials.
  • Induction Charging: Charges are redistributed without contact with the charged body.

 

  1. Difference between Voltage and Current
    Answer:
  • Voltage: Push that drives current through the circuit; measured in volts.
  • Current: Flow of electric charge in the circuit; measured in amperes.

 

  1. Difference between Earth Wire and Neutral Wire Connection
    Answer:
  • Earth Wire: Connected to metal body of appliances for safety.
  • Neutral Wire: Connected to the supply to complete the circuit.

 

  1. Difference between Lightning and Static Electricity
    Answer:
  • Lightning: Sudden discharge of static electricity in clouds.
  • Static Electricity: Accumulation of charges at rest on a body.

 

  1. Difference between Fuse Wire and Live Wire
    Answer:
  • Fuse Wire: Melts to break the circuit when current exceeds safe limit.
  • Live Wire: Carries current to the appliance under normal conditions.

 

  1. Difference between AC Appliance and DC Appliance
    Answer:
  • AC Appliance: Works with alternating current; voltage changes direction periodically.
  • DC Appliance: Works with direct current; voltage remains constant in one direction.

Assertion and Reason

The correct answer indicated as:

  • A: Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
  • B: Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
  • C: Assertion is true, Reason is false
  • D: Assertion is false, Reason is true
  1. Assertion (A): A fuse is connected in the live wire of a circuit.
    Reason (R): The fuse protects the circuit by breaking the circuit if excess current flows.
    Answer: A

 

  1. Assertion (A): MCB can be reset after tripping.
    Reason (R): MCB provides a permanent break in the circuit when overloaded.
    Answer: C

 

  1. Assertion (A): Household appliances are connected in parallel.
    Reason (R): Parallel connection allows each appliance to receive full voltage.
    Answer: A

 

  1. Assertion (A): Two bulbs in series glow dimmer than in parallel.
    Reason (R): In series, voltage is shared among bulbs.
    Answer: A

 

  1. Assertion (A): The earth wire is connected to the metal body of appliances.
    Reason (R): Earthing prevents electric shocks.
    Answer: A

 

  1. Assertion (A): Static electricity is a form of electric charge at rest.
    Reason (R): Charges at rest exert no force.
    Answer: C

 

  1. Assertion (A): A lightning conductor protects a building from lightning.
    Reason (R): It provides a low resistance path for lightning to the earth.
    Answer: A

 

  1. Assertion (A): Copper is a good conductor of electricity.
    Reason (R): Copper allows free movement of electrons.
    Answer: A

 

  1. Assertion (A): Rubber is used as insulation for wires.
    Reason (R): Rubber is a good conductor of electricity.
    Answer: D

 

  1. Assertion (A): The live wire is colour-coded red.
    Reason (R): Colour coding helps identify wires.
    Answer: A

 

  1. Assertion (A): A pith ball electroscope shows movement when charged.
    Reason (R): Like charges repel each other.
    Answer: A

 

  1. Assertion (A): A gold leaf electroscope has two leaves that diverge when charged.
    Reason (R): Opposite charges repel each other.
    Answer: C

 

  1. Assertion (A): Electrical energy consumed is calculated as W = P × t.
    Reason (R): Power multiplied by time gives energy consumed.
    Answer: A

 

  1. Assertion (A): Short-circuit occurs when live and neutral wires touch directly.
    Reason (R): It allows uncontrolled flow of current.
    Answer: A

 

  1. Assertion (A): Overloading can cause heating or fire.
    Reason (R): Excess current produces heat in the circuit.
    Answer: A

 

  1. Assertion (A): AC supply changes direction periodically.
    Reason (R): AC supply has a frequency of 50 Hz in India.
    Answer: B

 

  1. Assertion (A): DC current flows only in one direction.
    Reason (R): DC current frequency is zero.
    Answer: A

 

  1. Assertion (A): Fuse has a low melting point.
    Reason (R): It melts to break the circuit when current exceeds safe limit.
    Answer: A

 

  1. Assertion (A): Lightning is a discharge of static electricity.
    Reason (R): Lightning carries direct current through clouds.
    Answer: C

 

  1. Assertion (A): Electric meter measures energy consumption.
    Reason (R): It counts the number of units used.
    Answer: A

 

  1. Assertion (A): Positive and negative charges attract each other.
    Reason (R): Like charges repel each other.
    Answer: C

 

  1. Assertion (A): Charging by rubbing is called friction.
    Reason (R): Charges are transferred due to contact.
    Answer: C

 

  1. Assertion (A): Charging a conductor by touching is conduction.
    Reason (R): Charges are transferred by direct contact.
    Answer: A

 

  1. Assertion (A): Charging a conductor without contact is induction.
    Reason (R): It involves no direct transfer of charges.
    Answer: A

 

  1. Assertion (A): A fuse is rated slightly above normal current.
    Reason (R): So that it blows under normal conditions.
    Answer: C

 

  1. Assertion (A): Two bulbs in parallel glow brighter than in series.
    Reason (R): Voltage across each bulb is equal to supply voltage.
    Answer: A

 

  1. Assertion (A): A rod rubbed with silk becomes positively charged.
    Reason (R): Electrons are transferred from rod to silk.
    Answer: A

 

  1. Assertion (A): A rod rubbed with fur becomes negatively charged.
    Reason (R): Rod gains electrons from fur.
    Answer: A

 

  1. Assertion (A): AC supply is used in households.
    Reason (R): It is easy to transmit over long distances.
    Answer: A

 

  1. Assertion (A): Earthing prevents electric shocks.
    Reason (R): It provides a low resistance path for current to flow safely to the ground.
    Answer: A

 

  1. Assertion (A): Main switch controls electricity for the whole house.
    Reason (R): It can isolate the house from main supply.
    Answer: A

 

  1. Assertion (A): Distribution board contains MCBs for sub-circuits.
    Reason (R): It divides supply into manageable circuits.
    Answer: A

 

  1. Assertion (A): Meter measures electrical energy consumed.
    Reason (R): Measured in kilowatt-hour.
    Answer: A

 

  1. Assertion (A): Current increases if resistance decreases for a fixed voltage.
    Reason (R): Ohm’s Law: I = V/R.
    Answer: A

 

  1. Assertion (A): Rubber gloves protect from electric shocks.
    Reason (R): Rubber is an insulator.
    Answer: A

 

  1. Assertion (A): Fuse melts when current exceeds safe limit.
    Reason (R): Fuse has a low melting point.
    Answer: A

 

  1. Assertion (A): Lightning conductor is made of copper.
    Reason (R): Copper is a good conductor of electricity.
    Answer: A

 

  1. Assertion (A): Static electricity can attract light objects.
    Reason (R): Static charges exert forces on other charges.
    Answer: A

 

  1. Assertion (A): Electric charges at rest exert forces on each other.
    Reason (R): Like charges repel and unlike charges attract.
    Answer: A

 

  1. Assertion (A): Two bulbs in series share supply voltage.
    Reason (R): Each bulb receives the full voltage.
    Answer: C

 

  1. Assertion (A): Current in household circuits is AC.
    Reason (R): It flows in only one direction.
    Answer: C

 

  1. Assertion (A): Fuse is a safety device.
    Reason (R): It melts when current is too high.
    Answer: A

 

  1. Assertion (A): Electric meter shows units consumed.
    Reason (R): Each unit = 1 kWh.
    Answer: A

 

  1. Assertion (A): A conductor allows flow of electrons.
    Reason (R): Insulators prevent flow of electrons.
    Answer: B

 

  1. Assertion (A): Earthing is necessary for appliances with metallic body.
    Reason (R): It prevents electric shocks.
    Answer: A

 

  1. Assertion (A): Copper and aluminum are conductors.
    Reason (R): They have free electrons.
    Answer: A

 

  1. Assertion (A): Static electricity can cause sparks.
    Reason (R): Charges accumulate at rest and discharge suddenly.
    Answer: A

 

  1. Assertion (A): Series connection is used in household circuits.
    Reason (R): Series allows each appliance to get full voltage.
    Answer: D

 

  1. Assertion (A): Short-circuit can cause fire.
    Reason (R): Excess current flows through unintended path.
    Answer: A

 

  1. Assertion (A): Lightning conductor should be tall and pointed.
    Reason (R): To safely attract and divert lightning to the earth.
    Answer: A

True or False

  1. Live wire carries current to the appliance.
    Answer: True

 

  1. Neutral wire is connected to the metal body of an appliance.
    Answer: False

 

  1. Earth wire provides a safe path for excess current to flow to the ground.
    Answer: True

 

  1. Fuse melts when current exceeds its safe limit.
    Answer: True

 

  1. MCB can be reset after tripping.
    Answer: True

 

  1. Household appliances are usually connected in series.
    Answer: False

 

  1. In a parallel connection, each appliance receives full voltage.
    Answer: True

 

  1. Two bulbs in series glow brighter than in parallel.
    Answer: False

 

  1. Earthing prevents electric shocks.
    Answer: True

 

  1. Static electricity is a form of electric charge at rest.
    Answer: True

 

  1. Lightning is a sudden discharge of static electricity.
    Answer: True

 

  1. Lightning conductor is used to attract lightning to the ground.
    Answer: True

 

  1. Copper is a poor conductor of electricity.
    Answer: False

 

  1. Rubber is used for insulation of wires.
    Answer: True

 

  1. The live wire is colour-coded black in India.
    Answer: False

 

  1. Neutral wire is colour-coded red.
    Answer: False

 

  1. Earth wire is colour-coded green or green-yellow.
    Answer: True

 

  1. Electroscope is used to detect electric charges.
    Answer: True

 

  1. Gold leaf electroscope has leaves that diverge when charged.
    Answer: True

 

  1. Pith ball electroscope uses small balls suspended on threads.
    Answer: True

 

  1. AC current flows in one direction only.
    Answer: False

 

  1. DC current flows in one direction only.
    Answer: True

 

  1. The household voltage in India is 220 V.
    Answer: True

 

  1. Household supply frequency in India is 60 Hz.
    Answer: False

 

  1. Overloading a circuit can cause heating and fire.
    Answer: True

 

  1. Short-circuit occurs when live and neutral wires touch each other directly.
    Answer: True

 

  1. Fuse is connected in the neutral wire.
    Answer: False

 

  1. MCB provides thermal or magnetic protection to the circuit.
    Answer: True

 

  1. Static charges repel or attract each other depending on their type.
    Answer: True

 

  1. Positive and negative charges repel each other.
    Answer: False

 

  1. Charging by rubbing is called friction.
    Answer: True

 

  1. Charging by touching is called induction.
    Answer: False

 

  1. Charging without contact is called conduction.
    Answer: False

 

  1. Electrical energy consumed = Power × Time.
    Answer: True

 

  1. Power consumed = Voltage × Current.
    Answer: True

 

  1. Two bulbs in series share supply voltage.
    Answer: True

 

  1. Two bulbs in parallel share voltage.
    Answer: False

 

  1. A battery provides AC current.
    Answer: False

 

  1. Lightning conductor is usually made of copper.
    Answer: True

 

  1. The main switch controls electricity for the entire house.
    Answer: True

 

  1. Distribution board contains MCBs or fuses for sub-circuits.
    Answer: True

 

  1. Electric meter shows electrical energy consumed in units.
    Answer: True

 

  1. Positive charge is carried by electrons.
    Answer: False

 

  1. Negative charge is carried by protons.
    Answer: False

 

  1. Neutral bodies have no net charge.
    Answer: True

 

  1. Friction, conduction, and induction are methods of charging a conductor.
    Answer: True

 

  1. Overhead transmission lines carry electricity at low voltage.
    Answer: False

 

  1. Copper and aluminum are good conductors of electricity.
    Answer: True

 

  1. Fuse protects against short-circuits and overloads.
    Answer: True

 

  1. Earthing is not necessary for plastic-bodied appliances.
    Answer: True

Long Answer Questions

  1. Explain household electricity and its components.
    Answer: Household electricity is the supply of electrical energy to homes for operating appliances. It consists of three wires: live wire (carries current to the appliance), neutral wire (returns current to the supply), and earth wire (safety wire connected to the metal body to prevent shocks).

 

  1. What is the function of a fuse in a household circuit?
    Answer: A fuse is a safety device that prevents excessive current from flowing through the circuit. It contains a thin wire that melts when the current exceeds a safe limit, breaking the circuit and preventing damage or fire.

 

  1. What is a Miniature Circuit Breaker (MCB) and how is it different from a fuse?
    Answer: An MCB is an automatic switch that trips when current exceeds a safe limit. Unlike a fuse, it can be reset after tripping and does not need replacement, providing convenience and safety in household circuits.

 

  1. Describe the supply of power from the generating station to a house.
    Answer: Electricity is generated at power stations and transmitted at high voltage through overhead transmission lines to reduce energy loss. It reaches the consumer via step-down transformers and distribution lines, finally entering homes through a distribution board with fuses and MCBs for safety.

 

  1. Explain the colour coding of live, neutral, and earth wires.
    Answer: In India, the live wire is red, the neutral wire is black, and the earth wire is green or green-yellow. Colour coding ensures easy identification and safe connections.

 

  1. What is the commercial unit of electrical energy?
    Answer: The commercial unit of electrical energy is 1 kilowatt-hour (kWh), which is the energy consumed when a 1 kW appliance runs for one hour.

 

  1. What is the function of an electric meter?
    Answer: An electric meter measures the electrical energy consumed by a house in units (kWh) and helps in billing.

 

  1. Explain the connection from the pole to the distribution board in a house.
    Answer: Power is supplied from a pole via a main switch to the distribution board, which divides electricity into sub-circuits protected by fuses or MCBs to ensure safety and controlled distribution to different appliances.

 

  1. Describe household electrical circuits with an example.
    Answer: Household circuits are generally parallel circuits, allowing each appliance to operate independently. For example, bulbs in different rooms are connected in parallel so that one bulb can fail without affecting others.

 

  1. Explain the experiment of two torch bulbs in series and parallel.
    Answer: In series, two bulbs share voltage, so they glow dimly. In parallel, each bulb receives full voltage, so they glow brightly. This demonstrates the difference between series and parallel connections.

 

  1. What is earthing and why is it necessary?
    Answer: Earthing involves connecting the metal body of appliances to the ground through an earth wire. It prevents electric shocks by providing a safe path for leakage current.

 

  1. What is meant by power rating of appliances?
    Answer: Power rating indicates the amount of electrical energy consumed per second by an appliance, expressed in watts (W) or kilowatts (kW).

 

  1. How is household consumption of electrical energy calculated?
    Answer: Consumption is calculated using the formula: Energy (kWh) = Power (kW) × Time (hours). It helps in estimating electricity bills.

 

  1. Explain the hazards of electricity in households.
    Answer: Hazards include electric shocks, burns, fires due to short-circuits or overloading, and damage to appliances. Proper wiring, fuses, MCBs, and precautions reduce these risks.

 

  1. List precautions to be taken while using electricity.
    Answer: Precautions include not touching appliances with wet hands, using insulated wires, avoiding overloading sockets, proper earthing, and installing fuses and MCBs.

 

  1. Define static electricity.
    Answer: Static electricity is the accumulation of electric charge on the surface of a body at rest, which does not flow like current but can cause attraction or repulsion of light objects.

 

  1. State the law of charges.
    Answer: Like charges repel each other, and unlike charges attract each other.

 

  1. Explain the conservation of charge.
    Answer: Electric charge can neither be created nor destroyed; it can only be transferred from one body to another.

 

  1. Describe charging by rubbing.
    Answer: Charging by rubbing occurs when two different materials are rubbed together, transferring electrons from one to the other. Example: Glass rod rubbed with silk becomes positively charged.

 

  1. Explain conduction method of charging.
    Answer: In conduction, a charged body transfers charge to a neutral conductor by direct contact, causing it to acquire the same type of charge.

 

  1. Explain induction method of charging.
    Answer: In induction, a charged body causes redistribution of charges in a nearby conductor without direct contact, resulting in opposite charges on different ends of the conductor.

 

  1. Differentiate between charging by conduction and induction.
    Answer: Conduction requires direct contact and gives the same type of charge, whereas induction requires no contact and produces opposite charges on different ends.

 

  1. Describe a pith ball electroscope.
    Answer: It consists of a small lightweight ball suspended on a thread. When a charged body is brought near, the ball is attracted or repelled, showing the presence of charge.

 

  1. Describe a gold leaf electroscope.
    Answer: It consists of a metal rod with thin gold leaves at the bottom. When charged, the leaves repel each other and diverge, indicating the presence of charge.

 

  1. What is atmospheric electricity?
    Answer: It refers to the electric charges present in the atmosphere, often observed as lightning during storms.

 

  1. Describe Benjamin Franklin’s experiment on lightning.
    Answer: Franklin demonstrated that lightning is electrical by drawing sparks from a pointed rod during a storm, proving that lightning is a discharge of static electricity.

 

  1. Explain lightning and its hazards.
    Answer: Lightning is a sudden discharge of static electricity from clouds to the ground, causing fires, damage to structures, and risk of injury or death.

 

  1. How does a lightning conductor work?
    Answer: A lightning conductor is a pointed metal rod connected to the earth. It attracts lightning and safely directs it to the ground, protecting buildings.

 

  1. Define electrical energy.
    Answer: Electrical energy is the energy consumed by an electrical device when current flows through it, producing work or heat.

 

  1. How is electrical energy related to power?
    Answer: Electrical energy consumed = Power × Time, where power is the rate at which energy is used.

 

  1. Explain the concept of electrical current.
    Answer: Electrical current is the flow of electric charge through a conductor, measured in amperes (A).

 

  1. Define voltage.
    Answer: Voltage is the potential difference between two points, which causes current to flow, measured in volts (V).

 

  1. Explain the difference between AC and DC.
    Answer: AC changes direction periodically, while DC flows in one direction only. AC is used in households, DC in batteries.

 

  1. What is the importance of colour coding in wires?
    Answer: It helps identify live, neutral, and earth wires to ensure safe connections and prevent accidents.

 

  1. How can two bulbs in parallel glow independently?
    Answer: In a parallel circuit, each bulb receives full voltage and has an independent path for current, so one bulb can fail without affecting others.

 

  1. Explain the function of the main switch.
    Answer: The main switch controls the supply of electricity to the entire house and isolates it for safety during maintenance.

 

  1. What is meant by overload in electrical circuits?
    Answer: Overload occurs when a circuit draws more current than it is designed for, causing heating and potential hazards.

 

  1. Explain short-circuit with an example.
    Answer: A short-circuit occurs when live and neutral wires touch directly, allowing uncontrolled current flow; for example, when bare wires touch.

 

  1. How do fuses prevent hazards?
    Answer: Fuses melt when excess current flows, breaking the circuit and preventing overheating or fire.

 

  1. How do MCBs prevent hazards?
    Answer: MCBs trip automatically when current exceeds safe limits and can be reset, providing protection against overloads and short-circuits.

 

  1. What is the difference between series and parallel circuits?
    Answer: In series, current is the same in all components but voltage divides; in parallel, voltage is the same across components but current divides.

 

  1. How can static electricity attract small objects?
    Answer: A charged body creates an electric field that exerts force on nearby small objects, causing attraction.

 

  1. Explain the importance of using good conductors in household wiring.
    Answer: Good conductors like copper allow free flow of electrons with low resistance, reducing energy loss and heating.

 

  1. Why should insulators be used in electrical appliances?
    Answer: Insulators prevent unwanted flow of current, ensuring safety and avoiding electric shocks.

 

  1. Describe an experiment to show charging by friction.
    Answer: Rub a glass rod with silk; the rod becomes positively charged and can attract small bits of paper, demonstrating transfer of electrons.

 

  1. Describe an experiment to show conduction of charge.
    Answer: Touch a charged rod to a neutral conductor; the conductor acquires the same charge, showing conduction.

 

  1. Describe an experiment to show induction of charge.
    Answer: Bring a charged rod near a neutral conductor without touching it; charges within the conductor redistribute, causing one end to become positively charged and the other negatively charged, demonstrating induction.

 

  1. Explain how electrical energy is billed in households.
    Answer: Electrical energy is measured in units (kWh) by an electric meter, and the bill is calculated by multiplying the number of units consumed by the cost per unit.

 

  1. Why is copper preferred over aluminum for wiring in households?
    Answer: Copper has lower resistance and higher conductivity than aluminum, reducing energy loss and heating in wires.

 

  1. Summarize the precautions to be taken while using electricity.
    Answer: Precautions include proper insulation of wires, using fuses or MCBs, earthing of appliances, avoiding wet hands while touching appliances, not overloading circuits, and keeping flammable materials away from electrical devices.

Give Reasons

  1. Why is the live wire red in colour?
    Answer: To easily identify it as the wire carrying current to the appliance.

 

  1. Why is the neutral wire black in colour?
    Answer: To distinguish it as the wire completing the circuit back to supply.

 

  1. Why is the earth wire green or green-yellow?
    Answer: To indicate it is for safety and provides a path to the ground.

 

  1. Why is earthing necessary for metallic appliances?
    Answer: It prevents electric shocks by directing leakage current to the ground.

 

  1. Why do fuses blow when current exceeds the safe limit?
    Answer: The fuse wire melts, breaking the circuit and preventing overheating or fire.

 

  1. Why can MCBs be reset after tripping?
    Answer: Because they act as automatic switches that do not melt, unlike fuses.

 

  1. Why are household appliances connected in parallel?
    Answer: So each appliance receives full voltage and operates independently.

 

  1. Why do bulbs in series glow dimmer than in parallel?
    Answer: Because voltage is divided among bulbs in series.

 

  1. Why is static electricity called so?
    Answer: Because the electric charge remains at rest and does not flow like current.

 

  1. Why do like charges repel each other?
    Answer: Because electrostatic force acts such that similar charges push away.

 

  1. Why do unlike charges attract each other?
    Answer: Because electrostatic force pulls opposite charges together.

 

  1. Why is copper used for household wiring?
    Answer: Because it has high conductivity and low resistance, minimizing energy loss.

 

  1. Why are fuses rated slightly above normal current?
    Answer: To allow normal current flow without unnecessary blowing of the fuse.

 

  1. Why is rubber used for insulation of wires?
    Answer: Because it is a good insulator and prevents leakage of current.

 

  1. Why does a lightning conductor have a pointed tip?
    Answer: To attract lightning and provide a safe path for discharge to earth.

 

  1. Why is voltage necessary in an electrical circuit?
    Answer: It provides the potential difference needed to drive current through the circuit.

 

  1. Why does a short-circuit cause heating and fire?
    Answer: Because excessive current flows through low resistance, generating heat.

 

  1. Why should appliances not be touched with wet hands?
    Answer: Because water conducts electricity and can cause electric shocks.

 

  1. Why is an electric meter used in households?
    Answer: To measure electrical energy consumed for billing purposes.

 

  1. Why does a gold leaf electroscope show divergence of leaves?
    Answer: Because like charges repel, causing the gold leaves to separate.

 

  1. Why does a pith ball move towards a charged object?
    Answer: Because of electrostatic attraction between opposite charges.

 

  1. Why does a rod become charged when rubbed with silk?
    Answer: Electrons are transferred from one material to another, creating charge.

 

  1. Why does a negatively charged rod repel electrons on a conductor during induction?
    Answer: Because like charges repel, pushing electrons to the far end.

 

  1. Why is AC used for household supply and not DC?
    Answer: Because AC is easy to transmit over long distances with less energy loss.

 

  1. Why does overloading a socket trip the MCB?
    Answer: Because current exceeds the safe limit, and MCB interrupts the circuit.

 

  1. Why does a bulb in parallel continue to glow when another bulb is removed?
    Answer: Because each bulb has an independent path for current in a parallel circuit.

 

  1. Why is aluminium sometimes used in transmission lines instead of copper?
    Answer: Because it is lighter and cheaper, though less conductive than copper.

 

  1. Why do we use high voltage for power transmission?
    Answer: To reduce current and minimize energy loss in the transmission lines.

 

  1. Why should distribution boards be installed properly?
    Answer: To divide electricity safely into sub-circuits and protect appliances.

 

  1. Why are fuses and MCBs connected in the live wire?
    Answer: To cut off current supply in case of fault and prevent hazards.

 

  1. Why does charging by induction not require contact?
    Answer: Because the electric field causes redistribution of charges in the conductor.

 

  1. Why are insulators used in high-voltage transmission?
    Answer: To prevent leakage of current from wires to poles or structures.

 

  1. Why does a bulb glow brighter in parallel than in series?
    Answer: Because it receives the full supply voltage in parallel.

 

  1. Why do lightning strikes cause fires without a conductor?
    Answer: Because the high voltage creates sparks that ignite flammable materials.

 

  1. Why should wires be properly insulated?
    Answer: To prevent accidental contact and electric shocks.

 

  1. Why does static electricity attract small objects like paper bits?
    Answer: Because the electric field of the charged body induces opposite charges on the paper.

 

  1. Why does a fuse wire melt faster when current is very high?
    Answer: Because heat generated (I²R) is proportional to the square of the current.

 

  1. Why are the leaves of a gold leaf electroscope made thin?
    Answer: To easily show divergence when small charges are present.

 

  1. Why is electricity dangerous in wet conditions?
    Answer: Because water lowers resistance, allowing current to flow through the body.

 

  1. Why is the main switch installed at the entrance of a house?
    Answer: To control the electricity supply to the whole house safely.

 

  1. Why is copper preferred for lightning conductors?
    Answer: Because of its high conductivity and durability.

 

  1. Why is it important to keep flammable materials away from electrical devices?
    Answer: To prevent fires caused by sparks or overheating.

 

  1. Why does a charged rod attract a neutral object?
    Answer: Because it induces opposite charges on the neutral object, causing attraction.

 

  1. Why do we use parallel circuits in homes instead of series circuits?
    Answer: So that appliances operate independently and receive full voltage.

 

  1. Why does a conductor become charged by rubbing?
    Answer: Electrons are transferred from one body to another during friction.

 

  1. Why should overhead transmission lines be kept high above the ground?
    Answer: To prevent accidental contact and reduce risk of electrocution.

 

  1. Why is electrical energy considered safer when properly grounded?
    Answer: Because leakage currents are directed safely to the earth, preventing shocks.

 

  1. Why should old or damaged wires be replaced immediately?
    Answer: To prevent short-circuits, shocks, or fire hazards.

 

  1. Why is it dangerous to touch a bare live wire?
    Answer: Because it can cause electric shock or even electrocution.

 

  1. Why do electricians test wires with a tester before connecting them?
    Answer: To ensure wires are live, neutral, or earth and prevent accidental hazards.

Arrange the Words 

Case Studies

  1. Ravi notices that a bulb in his series string of lights has fused. The other bulbs are dim.
    Question: Why do the remaining bulbs glow dimly?
    Answer: In a series circuit, the current is the same, and the voltage is divided among bulbs. If one bulb fuses, the current decreases, causing the others to glow dimly.

 

  1. A house has appliances connected in parallel. One appliance stops working.
    Question: Why do other appliances still work?
    Answer: In a parallel circuit, each appliance has its independent path, so others continue to receive full voltage.

 

  1. An MCB trips frequently in a home.
    Question: What could be the reason?
    Answer: Frequent tripping occurs due to overloading of the circuit or a short-circuit; MCB protects appliances by interrupting excess current.

 

  1. A child touches a metallic appliance with wet hands and gets a shock.
    Question: How could this have been prevented?
    Answer: By proper earthing of appliances and avoiding contact with wet hands; safety measures prevent electric shocks.

 

  1. A glass rod is rubbed with silk and brought near a pith ball. The pith ball moves towards the rod.
    Question: Explain what happens.
    Answer: Rubbing charges the rod positively; the pith ball is neutral, and opposite charges attract, so it moves toward the rod.

 

  1. Lightning strikes a tall building without a lightning conductor and causes damage.
    Question: How can this damage be prevented?
    Answer: Installing a lightning conductor provides a safe path for discharge to earth, preventing structural damage.

 

  1. Copper wires in a household become hot.
    Question: Why does this happen?
    Answer: Excess current causes heating due to resistance (I²R), which can be prevented by proper fuse or MCB.

 

  1. An electric meter shows higher units than expected.
    Question: What might be the reason?
    Answer: Possible reasons include increased usage, faulty meter, or leakage current in ungrounded appliances.

 

  1. A fuse in a circuit melts even with normal current.
    Question: Why could this happen?
    Answer: Fuse rating may be too low or there may be loose connections causing localized heating.

 

  1. Two rods, glass and ebonite, are rubbed with silk and fur respectively. They attract small bits of paper.
    Question: Explain the observation.
    Answer: Rubbing causes transfer of electrons; glass becomes positively charged, ebonite negatively charged. Both attract neutral paper due to electrostatic force.

 

  1. A student observes sparks when removing a plug from a socket.
    Question: Why do sparks occur?
    Answer: Sparks occur due to sudden flow of current when contact is broken; switching off main supply before unplugging is safer.

 

  1. A metallic appliance gives a shock despite the fuse being intact.
    Question: What could be the reason?
    Answer: Possible leakage current due to damaged insulation; proper earthing would prevent shocks.

 

  1. Two bulbs are connected in series, one is replaced with a higher wattage bulb.
    Question: What happens to brightness?
    Answer: The higher wattage bulb requires more current; in series, current is limited by both bulbs, so brightness may be uneven or reduced.

 

  1. A rod is charged by induction without touching a conductor.
    Question: How is the conductor charged?
    Answer: The electric field of the rod redistributes charges in the conductor, leaving opposite charges at the near end.

 

  1. A household circuit trips when a heater and fan run together.
    Question: Explain the cause.
    Answer: Combined current exceeds safe limit (overload); MCB trips to prevent overheating or fire.

 

  1. A pith ball electroscope is repelled by a charged rod.
    Question: Why does repulsion occur?
    Answer: Both pith ball and rod have like charges, causing electrostatic repulsion.

 

  1. A lightning conductor is installed on a school building.
    Question: How does it protect the building?
    Answer: It provides a low-resistance path to earth, safely discharging lightning without damaging the structure.

 

  1. A child accidentally touches a live wire of a fan.
    Question: What safety measures prevent injury?
    Answer: Proper earthing, insulated wires, and MCBs prevent fatal electric shocks.

 

  1. An appliance runs slower than usual. The voltage supply is checked and found low.
    Question: Why does low voltage affect the appliance?
    Answer: Low voltage reduces current through the appliance, decreasing its performance or speed.

 

  1. A gold leaf electroscope shows divergence when a charged rod is brought near.
    Question: Explain the phenomenon.
    Answer: Like charges on the electroscope leaves repel each other, causing divergence; indicates presence of charge.

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