Class 12 Physics (Part I) Chapter 6 Electromagnetic Induction Quiz 13 (25 MCQs)

Quiz Instructions

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1. What is the contribution of Joseph Henry to the world of electromagnetism?
2. What is the principle behind AC generators?
3. What is the unit of self-inductance?
4. What factors affect the magnitude of induced EMF according to Faraday's Law?
5. Why transformers work with A.C. current but not D.C.
6. A circular coil carrying a current of radius R and number of turns N and if all the three that is the current I, radius R and number of turns N are doubled, then magnetic field at its centre becomes
7. A lamp rated at 12 V 60 W is connected to the secondary coil of a step-down transformer and is at full brightness. The primary coil is connected to a supply of 230 V. The transformer is 75% efficient.What is the current in the primary coil?
8. Observe:Check that Show loop data is on. Move the wire loop up, away from the magnet. If so, in which direction is the current moving, left or right?
9. The inductance in a coil plays the same role as
10. The SI units of induced emf is
11. A student investigates the output voltage induced across a coil of wire by a bar magnet. When will the induced voltage have the greatest value?
12. What type of current is produced by a battery?
13. A short bar magnet allowed to fall along the axis of horizontal metallic ring. Starting from rest, the distance fallen by the magnet in one second may be:-
14. Factors that affect the voltage generation in Faraday's experiment is
15. For electromagnetism, what does the right hand rule explain?
16. What is the relationship between the rate of change of magnetic flux and induced EMF?
17. What does EMF stand for?
18. What is the primary purpose of an AC generator?
19. There are 3 ways to increase the e.m.f, except?
20. Name the law which gives information about the polarity of induced EMF
21. If the direction of motion is reversed, the direction of the current .....
22. What is the result of cutting a magnet in half?
23. A 100% efficient transformer converts a 240 V input voltage to a 12 V output voltage. The output power of the transformer can be a maximum of 20 W.The output is connected to two 0.30 A bulbs in parallel. One of the bulbs fails. How does the current in the primary coil change?
24. For a coil having L = 2mH, current flow through it is I = tet then the time at which emf becomes zero:-
25. An a.c. generator contains a coil that rotates at a rate of 4500 revolutions per minute. What is the frequency of the alternating current?