Class 7 Science Chapter 10 Practice Question Answers - Electric Current and Its effects

Q1. Bulbs, wires, cells and switches are known as the of a circuit.
(a) element
(b) switch
(c) filament
(d) none of these
Ans: (a)
Wires, cells, switches and bulbs are elements of a circuit.

Q2. An element measures the flowing an electric current is:
(a) voltmeter
(b) filament
(c) circuit
(d) ammeter
Ans: (d)
An ammeter measures the flowing electric current.

Q3. An element measures the potential difference between two points in an electric circuit is:
(a) voltmeter
(b) filament
(c) circuit
(d) ammeter
Ans: (a)
A voltmeter measures the potential difference between two points.

Q4. Electric current has energy called:
(a) voltmeter
(b) filament
(c) electrical energy
(d) none of these
Ans: (c)
Electric current has electrical energy.

Q5. The magnetic material around the coil is wound is called:
(a) magnetic substance
(b) core
(c) soft iron
(d) none
Ans: (b)
The magnetic material around the coil is wound is called the core.

Q6. Very strong electromagnets are used for lifting:
(a) fans
(b) washing machines
(c) heavy iron pieces
(d) none of these
Ans: (c)
Very strong electromagnets are used for lifting heavy iron pieces.

Q7. A safety device that cuts off the current in a circuit if a sudden heavy current starts flowing in it is:
(a) fuse
(b) ammeter
(c) solenoid
(d) none of these
Ans: (a)
A fuse is a safety device that cuts off the current in case of a sudden surge.

Q8. A cylindrical coil of current carrying wire is:
(a) voltmeter
(b) ammeter
(c) fuse
(d) solenoid
Ans: (d)
A solenoid is a cylindrical coil of current-carrying wire.

Q9. A coil of insulated current- carrying wire wound around a piece of a magnetic substance is:
(a) voltmeter
(b) magnetic coil
(c) electromagnet
(d) none of these
Ans: (c) electromagnet
An electromagnet is a coil of insulated current-carrying wire wound around a magnetic substance.

Q10. Which of these is not a circuit element?
(a) potential difference
(b) voltmeter
(c) resistor
(d) battery
Ans: (c)
The resistor is not a circuit element.

Q11. Which of these appliances does not use an electromagnet?
(a) washing
(b) refrigerator
(c) room heater
(d) electric bell
Ans: (c)
The room heater does not use an electromagnet.

Q12. The fuse wire:
(a) never breaks
(b) breaks on shorting of wire
(c) breaks on flowing of excessive current
(d) both (b) and (c)
Ans: (d)
The fuse wire breaks on shorting of wire and excessive current flow.

Q13. Which of the following liquid is bad conductor of electricity:
(a) salted water
(b) orange juice
(c) lemon juice
(d) none of these
Ans: (d)
None of these Liquid is bad conductor of electricity.

Q14. Which of the following substance is a conductor of electricity:
(a) rubber
(b) paper
(c) nails
(d) plastic
Ans: (c)
Nails is conductors of electricity.

Q15. The electric current which is broken at some point is called:
(a) open circuit
(b) closed circuit
(c) short circuit
(d) long circuit
Ans: (a)
An open circuit is one where the current is broken at some point.

Q16.  symbol represents:
(a) cell
(b) battery
(c) closed circuit
(d) open key
Ans: (c)
This symbol represents a closed circuit.

Q17. What happens when an electric current passes through a conductor?

(a) It produces sound
(b) It produces heat
(c) It produces light
(d) It stops the flow of current

Answer: (b) 

When electric current flows through a conductor, it encounters resistance, which causes energy to be released in the form of heat. This is the principle behind devices like electric heaters and toasters.

Q18. A control consisting of an electrical device for making, breaking or changing the connections in a circuit is:
(a) a switch
(b) a key
(c) both (a) and (b)
(d) none of these
Ans: (c)

Both a switch and a key are devices used for making or breaking electrical connections.

Q19.   symbol represents:
(a) electric bulb
(b) electric cell
(c) battery
(d) wire
Ans: (b)
This symbol represents an electric cell.

Q20.   symbol represents:
(a) wire
(b) battery
(c) cell
(d) switch in ‘ON’ position
Ans: (d)
This symbol represents a switch in the ‘ON’ position.

Q21.  symbol represents:
(a) wire
(b) cell
(c) bulb
(d) battery
Ans: (a)
This symbol represents a wire.

Q22. Such a combination of two or more cells is called :
(a) wire
(b) cell
(c) bulb
(d) battery
Ans: (d)
A combination of two or more cells is called a battery.

Q23. The batteries used in tractors, trucks and inverters are also made from:
(a) cells
(b) wire
(c) battery
(d) none of these
Ans: (a)
The batteries used in tractors and trucks are made from cells.

Q24. The positive terminal of one cell is connected to the:
(a) positive terminal
(b) negative terminal
(c) wire
(d) bulb
Ans: (b)
The positive terminal of one cell is connected to the negative terminal of the next. 

Q25. The bulb glows as soon as the switch is moved to the:
(a) ‘ON’ position
(b) ‘OFF’ position
(c) both (a) and (b)
(d) none of these
Ans: (a)
The bulb glows when the switch is in the ‘ON’ position.

Q26. Which of the following materials is commonly used to make the filament of a light bulb?

Q28. The bulb has a thin wire called:
(a) battery
(b) cell
(c) filament
(d) none of these
Ans: (c)
The bulb has a thin wire called filament.

Q29. A fan used electric current to rotate to blow:
(a) air
(b) current
(c) wire
(d) none of these
Ans: (a)
A fan uses electric current to rotate and blow air.

Q30. What is the primary function of a switch in an electrical circuit?

(a) To increase the current
(b) To decrease the voltage
(c) To open or close the circuit
(d) To store electric charge

Answer: (c) 

​A switch is a device used to either open or close an electrical circuit. When the switch is "ON," it allows the current to flow, completing the circuit. When it is "OFF," the circuit is broken, and the current stops flowing.