Electromagnetic Induction free Model online Test2

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1. An e.m.f. of 16 volts is induced in a coil of inductance 4H. The rate of change of current must be _____.
64 A/s	32 A/s
16 A/s	4 A/s

2. The core of a coil has a length of 200 mm. The inductance of coil is 6 mH. If the core length is doubled, all other quantities, remaining the same, the in ductance will be ______.
3 mH	12 mH
24 mH	48 mH

3. The self inductances of two coils are 8 mH and 18 mH. If the co-efficients of coupling is 0.5, the mutual inductance of the coils is _____.
4 mH	5 mH
6 mH	12 mH

4. Two coils have inductances of 8 mH and 18 mH and a co-efficient of coupling of 0.5. If the two coils are connected in series aiding, the total inductance will be _____.
32 mH	38 mH
40 mH	48 mH

5. A 200 turn coil has an inductance of 12 mH. If the number of turns is increased to 400 turns, all other quantities (area, length etc.) remaining the same, the inductance will be ______.
6 mH	14 mH
24 mH	48 mH

6. Two coils have self-inductances of 10 H and 2 H, the mutual inductance being zero. If the two coils are connected in series, the total inductance will be _____.
6 H	8 H
12 H	24 H

7. In case all the flux from the current in coil 1 links with coil 2, the co-efficient of coupling will be ______.
2.0	1.0
0.5	zero

8. A coil with negligible resistance has 50V across it with 10 mA. The inductive reactance is ______.
50 ohms	500 ohms
1000 ohms	5000 ohms

9. A conductor 2 metres long moves at right angles to a magnetic field of flux density 1 tesla with a velocity of 12.5 m/s. The induced e.m.f. in the conductor will be _____.
10 V	15 V
25V	50V

10. Lenz's law is a consequence of the law of conservation of ______.
induced current	charge
energy	induced e.m.f.

11. A conductor carries 125 amperes of current under 60° to a magnetic field of 1.1 tesla. The force on the conductor will be nearly _____.
50 N	120 N
240 N	480 N

12. Find the force acting on a conductor 3m long carrying a current of 50 amperes at right angles to a magnetic field having a flux density of 0.67 tesla.
100 N	400 N
600 N	1000 N

13. The co-efficient of coupling between two air core coils depends on _____.
self-inductance of two coils only	mutual inductance between two coils only
mutual inductance and self inductance of two coils	none of the above

14. An average voltage of 10 V is induced in a 250 turns solenoid as a result of a change in flux which occurs in 0.5 second. The total flux change is _____.
20 Wb	2 Wb
0.2 Wb	0.02 Wb

15. A 500 turns solenoid develops an average induced voltage of 60 V. Over what time interval must a flux change of 0.06 Wb occur to produce such a voltage ?
0.01 s	0.1 s
0.5 s	5 s

16. Which of the fpllowing inductor will have the least eddy current losses ?
Air core	Laminated iron core
Iron core	Powdered iron core

17. A coil induces 350 mV when the current changes at the rate of 1 A/s. The value of inductance is _____.
3500 mH	350 mH
250 mH	150 mH

18. Two 300 uH coils in series without mutual coupling have a total inductance of _____.
300 uH	600 uH
150 uH	75 uH

19. Current changing from 8 A to 12 A in one second induced 20 volts in a coil. The value of inductance is _____.
5 mH	10 mH
5 H	10 H

20. Which circuit element(s) will oppose the change in circuit current ?
Resistance only	Inductance only
Capacitance only	Inductance and capacitance