Q1. What is the purpose of using an electric cell in devices like torches and clocks?
a) To provide a continuous supply of electricity
b) To light up the device
c) To produce electricity from chemicals stored inside
d) To connect different parts of the device
Answer: c) To produce electricity from chemicals stored inside
Explanation: An electric cell generates electricity from the chemicals stored within it. This electricity is then used to power devices like torches, clocks, and radios.
Q2. What happens when the chemicals in an electric cell are used up?
a) The cell recharges automatically
b) The cell can be refilled with chemicals
c) The electric cell stops producing electricity
d) The cell becomes a conductor of electricity
Answer: c) The electric cell stops producing electricity
Explanation: Once the chemicals in an electric cell are exhausted, it ceases to produce electricity and must be replaced with a new one.
Q3. Which part of the electric bulb emits light when electricity passes through it?
a) The glass case
b) The metallic base
c) The filament
d) The terminals
Answer: c) The filament
Explanation: The filament of the bulb is the thin wire that emits light when electric current passes through it.
Q4. What is the function of the filament in an electric bulb?
a) To connect the bulb to the electric cell
b) To protect the bulb from overheating
c) To emit light when electric current passes through it
d) To act as a switch for the bulb
Answer: c) To emit light when electric current passes through it
Explanation: The filament in an electric bulb is a thin wire that emits light when electric current passes through it. This is the primary function of the filament in the operation of a light bulb.
Q5. Why are electric cells and bulbs designed with two terminals?
a) To make them easier to handle
b) To allow the passage of electricity in one direction
c) To create a closed electric circuit for the flow of current
d) To increase their lifespan
Answer: c) To create a closed electric circuit for the flow of current
Explanation: Electric cells and bulbs have two terminals to create a closed circuit, allowing for the controlled flow of electric current.
Q6. What is the role of a switch in an electric circuit?
a) To increase the flow of electricity
b) To break or complete the electric circuit
c) To change the direction of current
d) To measure the amount of current
Answer: b) To break or complete the electric circuit
Explanation: A switch is a simple device used to either break the circuit, stopping the flow of electricity, or to complete it, allowing electricity to flow.
Q7. Which materials are considered good conductors of electricity?
a) Rubber and wood
b) Glass and thermo Col
c) Copper and aluminum
d) Cotton and paper
Answer: c) Copper and aluminum
Explanation: Materials like copper and aluminum are good conductors of electricity, allowing electric current to pass through them easily.
Q8. What determines whether a material is a conductor or an insulator in an electric circuit?
a) Its color and texture
b) Its ability to allow electric current to pass through it
c) Its weight and size
d) Its temperature and state of matter
Answer: b) Its ability to allow electric current to pass through it
Explanation: The key factor distinguishing conductors from insulators is the material’s ability to allow electric current to pass through it. Conductors allow current flow, while insulators do not.
Q9. What is the main reason for an electric bulb to fuse?
a) The glass case breaks
b) The filament remains intact
c) The metallic base corrodes
d) A break in the filament
Answer: d) A break in the filament
Explanation: A common reason for an electric bulb to fuse is a break in its filament. When the filament breaks, the path for electric current is interrupted, preventing the bulb from lighting up.
Q10. Why is it advised to never connect the two terminals of an electric cell directly?
a) It will increase the cell’s life
b) It can cause the cell to recharge
c) It may use up the cell’s chemicals very fast
d) It will make the cell a better conductor
Answer: c) It may use up the cell’s chemicals very fast
Explanation: Connecting the two terminals of an electric cell directly without a device like a bulb in between can lead to rapid consumption of the cell’s chemicals, causing it to stop working sooner.
Q11. In the context of electric circuits, what does a closed circuit indicate?
a) The circuit is not functioning
b) There is a gap in the circuit
c) The circuit provides a complete path for current to flow
d) The circuit only works with a switch
Answer: c) The circuit provides a complete path for current to flow
Explanation: A closed circuit means that there is a complete path for the electric current to flow from one terminal of the cell to the other, allowing devices like bulbs to function.
Q12. What happens to an electric bulb when the switch is turned off?
a) The bulb receives more electricity
b) The bulb’s filament breaks
c) The circuit is broken, stopping the flow of current
d) The bulb switches to a lower power mode
Answer: c) The circuit is broken, stopping the flow of current
Explanation: Turning off the switch in an electric circuit breaks the circuit, stopping the flow of electric current, and causing the bulb to stop glowing.
Q13. Which material is not a good conductor of electricity?
a) Copper
b) Aluminum
c) Rubber
d) Iron
Answer: c) Rubber
Explanation: Rubber is an insulator, not a conductor. It does not allow electric current to pass through it, unlike conductors such as copper, aluminum, and iron.
Q14. What does it mean if a bulb glows when connected to a “conduction tester”?
a) The bulb is fused
b) The tester is faulty
c) The material being tested is a conductor
d) The material being tested is an insulator
Answer: c) The material being tested is a conductor
Explanation: If a bulb glows when connected to a conduction tester, it indicates that the material being tested allows electric current to pass through it, meaning it is a conductor.
Q15. Why should an electrician use tools with insulated handles while working on electrical circuits?
a) To improve grip
b) To prevent electric shock
c) To increase the tool’s durability
d) To enhance the tool’s performance
Answer: b) To prevent electric shock
Explanation: Insulated handles on tools like screwdrivers and pliers prevent electric shock. Since the body is a conductor of electricity, the insulation provides a safety barrier while working on electrical circuits.
Q16. What is the role of an electric switch in a circuit?
a) To increase the voltage
b) To decrease the resistance
c) To break or complete the circuit
d) To change the direction of current
Answer: c) To break or complete the circuit
Explanation: An electric switch is used to either break (turn off) or complete (turn on) an electric circuit. It controls the flow of electricity in the circuit.
Q17. Which of the following is not a characteristic of an electric cell?
a) It can be recharged once used up
b) It has two terminals
c) It produces electricity from chemicals
d) It is used in devices like torches and clocks
Answer: a) It can be recharged once used up
Explanation: An electric cell, once used up, cannot be recharged (in the context of simple cells used in torches and clocks). It needs to be replaced with a new one.
Q18. Why are materials like rubber and plastic used in the handles of electrical appliances?
a) For aesthetic reasons
b) They are good conductors of electricity
c) They are cheap materials
d) They are insulators and prevent electric shock
Answer: d) They are insulators and prevent electric shock
Explanation: Rubber and plastic are used in the handles of electrical appliances because they are insulators. They do not allow electric current to pass through, thus preventing electric shock.
Q19. How does an electric bulb glow in a circuit?
a) By heating the glass case
b) When the switch is in the ‘off’ position
c) When current passes through its filament
d) Through the movement of the metal base
Answer: c) When current passes through its filament
Explanation: An electric bulb glows when electric current passes through its filament. The filament heats up and emits light.
Q20. What is the primary function of an electric switch in a circuit?
a) To reduce the electricity bill
b) To regulate the current flow
c) To control the turning on and off of the circuit
d) To change the direction of the current
Answer: c) To control the turning on and off of the circuit
Explanation: The primary function of an electric switch in a circuit is to control the turning on and off of the circuit. It either completes or breaks the circuit.
Q21. In a simple electric circuit, the direction of current is taken to be from:
a) Negative to positive terminal of the electric cell
b) Positive to negative terminal of the electric cell
c) Metal base to the filament of the bulb
d) Filament to the metal base of the bulb
Answer: b) Positive to negative terminal of the electric cell
Explanation: In an electric circuit, the direction of current is conventionally taken to be from the positive to the negative terminal of the electric cell.
Q22. What happens when there is a break in the filament of an electric bulb?
a) The bulb glows brighter
b) The path of the current is uninterrupted
c) No current passes through the bulb
d) The bulb switches to a lower power mode
Answer: c) No current passes through the bulb
Explanation: A break in the filament of an electric bulb means a break in the path of the current. As a result, no current passes through the bulb, and it does not light up.
Q23. What material is typically not used to make wires for electric circuits?
a) Copper
b) Aluminum
c) Wood
d) Iron
Answer: c) Wood
Explanation: Wood is an insulator and is not used for making wires in electric circuits. Conductive materials like copper, aluminum, and iron are used for this purpose.
Q24. The glowing of a bulb in a conduction tester indicates that the material being tested is:
a) A good insulator
b) Not suitable for electric circuits
c) A good conductor
d) Hazardous for use in electrical appliances
Answer: c) A good conductor
Explanation: The glowing of a bulb in a conduction tester indicates that the material being tested allows electric current to pass through it, meaning it is a good conductor.
Q25. What is the function of the metal cap on an electric cell?
a) It acts as the negative terminal.
b) It serves as the positive terminal.
c) It is used for aesthetic purposes.
d) It protects the cell from physical damage.
Answer: b) It serves as the positive terminal.
Explanation: The metal cap on an electric cell serves as the positive terminal, while the metal disc on the other side acts as the negative terminal.
Q26. Why is it important to not touch electric wires or sockets with wet hands?
a) It can cause the circuit to break.
b) The electricity can be less effective.
c) It can lead to a severe electric shock.
d) It makes the wires corrode faster.
Answer: c) It can lead to a severe electric shock.
Explanation: Touching electric wires or sockets with wet hands is dangerous because water is a good conductor of electricity, increasing the risk of electric shock.
Q27. What is the consequence of connecting the two terminals of an electric cell directly without a device like a bulb?
a) The cell will last longer.
b) The cell will recharge itself.
c) The cell will produce more electricity.
d) The chemicals in the cell will get used up very fast.
Answer: d) The chemicals in the cell will get used up very fast.
Explanation: Connecting the two terminals of an electric cell directly without a device like a bulb leads to rapid consumption of the cell’s chemicals, causing it to stop working sooner.
Q28. Why do electric bulbs and cells have two terminals each?
a) To double the power output.
b) To make them easier to manufacture.
c) To create a closed electric circuit for the flow of current.
d) To allow for easy replacement.
Answer: c) To create a closed electric circuit for the flow of current.
Explanation: Both electric bulbs and cells have two terminals to create a closed electric circuit. This setup allows for the controlled flow of electric current.
Q29. What does it indicate if an electric bulb does not glow even when connected to a cell?
a) The bulb is of high wattage.
b) The cell is very powerful.
c) The bulb might be fused.
d) The cell is not powerful enough.
Answer: c) The bulb might be fused.
Explanation: If an electric bulb does not glow when connected to a cell, it may indicate that the bulb is fused, often due to a break in its filament.
Q30. What type of materials should be used for making the handles of electrical appliances?
a) Conductors of electricity.
b) Magnetic materials.
c) Insulators of electricity.
d) Flexible materials.
Answer: c) Insulators of electricity.
Explanation: The handles of electrical appliances should be made of insulating materials to prevent electric shock and ensure safe handling.
Q31. Why are copper and aluminum commonly used for making electric wires?
a) They are inexpensive.
b) They are lightweight.
c) They are good conductors of electricity.
d) They are easily available.
Answer: c) They are good conductors of electricity.
Explanation: Copper and aluminum are commonly used for making electric wires because they are good conductors of electricity, allowing electric current to pass through them easily.
Q32. What is the role of a switch in a homemade electric torch, as described in the chapter?
a) To increase the brightness of the bulb.
b) To change the color of the light.
c) To break or complete the electric circuit.
d) To recharge the electric cell.
Answer: c) To break or complete the electric circuit.
Explanation: In a homemade electric torch, the switch’s role is to break or complete the electric circuit, effectively turning the torch on or off.
Q33. Which of the following is not a use of electricity?
a) Operating pumps
b) Lighting homes and roads
c) Heating and cooling
d) Increasing humidity
Answer: d) Increasing humidity
Explanation: Electricity is commonly used for operating pumps, lighting, and heating or cooling. However, increasing humidity is not typically a direct use of electricity.
Q34. Why is a torch used when there is a failure in the supply of electricity?
a) To conserve electricity
b) To provide light
c) To generate electricity
d) To test the electric circuit
Answer: b) To provide light
Explanation: A torch is used to provide light in situations where there is a failure in the supply of electricity, such as power outages.
Q35. What is the main purpose of the glass case of a torch bulb?
a) To conduct electricity
b) To protect the filament
c) To make the bulb look bigger
d) To increase the intensity of light
Answer: b) To protect the filament
Explanation: The glass case of a torch bulb is designed to protect the filament inside the bulb.
Q36. In the electric circuit experiments described in the chapter, what is the significance of using wires with differently colored plastic coverings?
a) To make the circuit look colorful
b) To easily identify the different wires
c) To increase the flow of electricity
d) To reduce the risk of electric shocks
Answer: b) To easily identify the different wires
Explanation: Using wires with differently colored plastic coverings in electric circuit experiments helps in easily identifying and distinguishing the different wires.
Q37. What is the purpose of a filament in an electric bulb?
a) To connect the terminals
b) To emit light when electric current passes through it
c) To act as a switch
d) To increase the voltage
Answer: b) To emit light when electric current passes through it
Explanation: The filament in an electric bulb emits light when electric current passes through it.
Q38. What happens when the two terminals of the electric cell are not connected in a circuit?
a) The cell recharges itself
b) The cell becomes a conductor
c) The cell stops producing electricity
d) The bulb connected to the cell will still glow
Answer: c) The cell stops producing electricity
Explanation: When the two terminals of the electric cell are not connected in a circuit, there is no path for electric current to flow, so the cell stops producing electricity.
Q39. Which of the following materials would not allow electric current to pass through?
a) Copper
b) Rubber
c) Aluminum
d) Iron
Answer: b) Rubber
Explanation: Rubber is an insulator and does not allow electric current to pass through it, unlike conductive materials like copper, aluminum, and iron.
Q40. In an electric circuit, if a switch is in the ‘off’ position, what does it mean?
a) The circuit is broken
b) The circuit is complete
c) The current flow is reversed
d) The voltage is increased
Answer: a) The circuit is broken
Explanation: When a switch in an electric circuit is in the ‘off’ position, it means that the circuit is broken, and no current flows through it.
Q41. What does the positive (+) sign on an electric cell indicate?
a) The negative terminal
b) The terminal that should be connected first
c) The side that should face upwards
d) The positive terminal
Answer: d) The positive terminal
Explanation: The positive (+) sign on an electric cell indicates the positive terminal, which is one of the two terminals of the cell.
Q42. Why should you never experiment with electric wires and sockets?
a) It can disrupt the power supply
b) It can cause severe injuries or even death
c) It can damage the wires
d) It will increase the electricity bill
Answer: b) It can cause severe injuries or even death
Explanation: Experimenting with electric wires and sockets is extremely dangerous and can cause severe injuries or even death due to electric shock or electrocution.
Q43. What is the purpose of the metal tip at the center of the base of a torch bulb?
a) To act as the negative terminal
b) To increase the brightness of the bulb
c) To protect the filament
d) To act as one of the two terminals of the bulb
Answer: d) To act as one of the two terminals of the bulb
Explanation: The metal tip at the center of the base of a torch bulb acts as one of the two terminals of the bulb, necessary for completing the electric circuit.
Q44. In the experiment described in the chapter, what happens if the free ends of the wires in the circuit are not connected properly?
a) The bulb glows brighter
b) The electric cell recharges
c) The bulb does not glow
d) The circuit becomes a conductor
Answer: c) The bulb does not glow
Explanation: If the free ends of the wires in the circuit are not connected properly, the circuit is incomplete, and the bulb will not glow due to the lack of current flow.
Q45. Why is air considered an insulator?
a) It is invisible
b) It does not allow electric current to pass through it
c) It is a gas
d) It cools down the circuit
Answer: b) It does not allow electric current to pass through it
Explanation: Air is considered an insulator because it does not allow electric current to pass through it under normal conditions.
Q46. In an electric circuit, what happens when the switch is turned on?
a) The circuit remains incomplete
b) The circuit is completed, allowing current to flow
c) The voltage in the circuit decreases
d) The circuit becomes an insulator
Answer: b) The circuit is completed, allowing current to flow
Explanation: When the switch in an electric circuit is turned on, it completes the circuit, allowing electric current to flow through it.
Q47. What is the primary use of electrical plugs and sockets in a circuit?
a) To decrease electrical resistance
b) To connect and disconnect the circuit from the power source
c) To store electricity
d) To control the direction of the current
Answer: b) To connect and disconnect the circuit from the power source
Explanation: Electrical plugs and sockets are used to connect and disconnect appliances and devices from the power source safely and conveniently.
Q48. Which of the following materials is a conductor of electricity?
a) Wood
b) Glass
c) Copper
d) Thermo Col
Answer: c) Copper
Explanation: Copper is a good conductor of electricity, meaning it allows electric current to pass through it easily, unlike insulators such as wood, glass, and Thermo Col.