MCQ Questions for Class 7 Science: Ch 14 Electric Current and Its effects

MCQ Questions for Class 7 Science: Ch 14 Electric Current and Its effects

1. Electromagnet loses its magnetic property when
(a) Current is very high
(b) Current is switched OFF
(c) Heat is increased
(d) Current is switched ON
► (b) Current is switched OFF

2. A ____________ is used in torches.
(a) Generator
(b) Fuse
(c) Secondary cell
(d) Dry cell
► (d) Dry cell

3. Electromagnet is used in
(a) Battery
(b) Dry cell
(c) Electric bell
(d) Fuse
► (c) Electric bell

4. A device which prevents or allows the current to flow through it
(a) Motor
(b) Terminal
(c) Conductor
(d) Switch
► (d) Switch

5. The metal which is poor conductor of electricity is
(a) Gold
(b) Iron
(c) Aluminium
(d) Mercury
► (d) Mercury

6. Electric current is measured by a device called
(a) Voltmeter
(b) Ammeter
(c) Electroscope
(d) None of these
► (b) Ammeter

7. A device that break the electric circuit in case of excess current is called
(a) Switch
(b) Fuse wire
(c) Voltmeter
(d) Earth wire
► (b) Fuse wire

8. Study of relationship between electricity and magnetism is called
(a) Current electricity       
(b) Electric magnetism
(c) Magneto electricity
(d) Electromagnetism
► (d) Electromagnetism

9. Coils of heating devices are made up of
(a) Mercury
(b) Nichrome
(c) Copper
(d) Tungsten
► (b) Nichrome

10. Electromagnet is based on
(a) Chemical effect of electric current
(b) Heating effect of electric current
(c) Magnetic effect of electric current
(d) Electro-chemical effect of electric current
► (c) Magnetic effect of electric current

11. Filament of electric bulb is made up of
(a) Nichrome
(b) Tungsten
(c) Silver
(d) Copper
► (b) Tungsten

12. Fuse wire is made up of alloys of
(a) High melting point
(b) Low melting point
(c) Low boiling point
(d) None of these
► (b) Low melting point

13. Wire carrying current produce attracts the magnetic material due to
(a) Magnetic field
(b) Chemical effect
(c) Heating effect
(d) All of these
► (a) Magnetic field

14. Fuse wire is used in electric circuit to prevent
(a) Prevent the ammeter
(b) Us from electric shock
(c) Electrical appliances and circuit
(d) Prevent the insulator
► (c) Electrical appliances and circuit

15. Why are symbols used for electronic components?
(a) It makes it easier to draw the circuit diagrams
(b) It is essential to draw the circuit diagrams
(c) It helps to show the direction of flow of current in a circuit
(d) All of the above
► (a) It makes it easier to draw the circuit diagrams

16. Heating effect of electric current is used in
(a) Electric watch
(b) Bread toaster
(c) Switch
(d) None of these
► (b) Bread toaster

17. In electrical wiring, the wire with black insulation is usually
(a) Fuse wire
(b) Live wire
(c) Earth wire
(d) Neutral wire
► (d) Neutral wire

18. MCB in electric circuit stand for
(a) Miniature circuit breaker
(b) Maximum current breaker
(c) Minimum current breaker
(d) Molar current breaker
► (a) Miniature circuit breaker

19. When electric current flows through a conductor, the conductor becomes
(a) liquid
(b) vapor
(c) hot
(d) cold
► (c) hot

20. Electric current is said to pass through a wire when
(a) Only proton pass through it
(b) Only electron passes through it
(c) No particle pass through it
(d) Both electron and neutron pass through it
► (b) Only electron passes through it

21. Which of the following materials is a conductor?
(a) Silver
(b) Rubber
(c) Cloth
(d) Plastic
► (a) Silver

22. A device that converts the electrical energy into heat energy is
(a) Motor
(b) Heater
(c) MP3
(d) Fan
► (b) Heater

23. Nichrome is used a coil of heater because
(a) It has high resistance and high melting point
(b) Low resistance and high melting point
(c) High resistance and low melting point
(d) None of the above
► (a) It has high resistance and high melting point

24. A fuse is fixed in a circuit in order to
(a) decrease the amount of current
(b) increase the amount of current
(c) increase the power consumed in the circuit
(d) safeguard against excessive current
► (d) safeguard against excessive current
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