Electromagnetic Induction Objective Questions - ObjectiveBooks

# Practice Test: Question Set - 04

1. Which of the following circuit element stores energy in the electromagnetic field?
(A) Inductance
(B) Condenser
(C) Variable resistor
(D) Resistance

2. 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
(A) 6 H
(B) 8 H
(C) 12 H
(D) 24 H

3. In an iron cored coil the iron core is removed so that the coil becomes an air cored coil. The inductance of the coil will
(A) Increase
(B) Decrease
(C) Remain the same
(D) Initially increase and then decrease

4. The direction of induced e.m.f. can be found by
(A) Laplace's law
(B) Lenz's law
(C) Fleming's right hand rule
(D) Kirchhoff s voltage law

5. Mutually inductance between two magnetically coupled coils depends on
(A) Permeability of the core
(B) The number of their turns
(C) Cross-sectional area of their common core
(D) All of the above

6. Which of the following circuit elements will oppose the change in circuit current?
(A) Capacitance
(B) Inductance
(C) Resistance
(D) All of the above

7. Which of the following is unit of inductance?
(A) Ohm
(B) Henry
(C) Ampere turns
(D) Weber/metre

8. 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
(A) 6 mH
(B) 146 mH
(C) 24 mH
(D) 48 mH

9. 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
(A) 50 N
(B) 120 N
(C) 240 N
(D) 480 N

10. Lenz's law is a consequence of the law of conservation of
(A) Induced current
(B) Charge
(C) Energy
(D) Induced e.m.f.

11. The inductance of a coil will increase under all the following conditions except
(A) When more length for the same number of turns is provided
(B) When the number of turns of the coil increase
(C) When more area for each turn is provided
(D) When permeability of the core increases

12. Two 300 uH coils in series without mutual coupling have a total inductance of
(A) 300 uH
(B) 600 uH
(C) 150 uH
(D) 75 uH

13. A coil is wound on iron core which carries current I. The self-induced voltage in the coil is not affected by
(A) Variation in coil current
(B) Variation in voltage to the coil
(C) Change of number of turns of coil
(D) The resistance of magnetic path

14. The polarity of the induced voltage can be determined by using the left-hand generator rule.
(A) Yes
(B) No

15. Both the number of turns and the core length of an inductive coil are doubled. Its self-inductance will be
(A) Unaffected
(B) Doubled
(C) Halved