Induction Electrical Questions and Answers - Set 02 - ObjectiveBooks

# Practice Test: Question Set - 02

1. The self inductances of two coils are 8 mH and 18 mH. If the coefficient of coupling is 0.5, the mutual inductance of the coils is
(A) 4 mH
(B) 5 mH
(C) 6 mH
(D) 12 mH

2. Which of the following is not a unit of inductance?
(A) Henry
(B) Coulomb/volt ampere
(C) Volt second per ampere
(D) All of the above

3. Air-core coils are practically free from
(A) Hysteresis losses
(B) Eddy current losses
(C) Both (A) and (B)
(D) None of the above

4. The property of coil by which a counter e.m.f. is induced in it when the current through the coil changes is known as
(A) Self-inductance
(B) Mutual inductance
(C) Series aiding inductance
(D) Capacitance

5. 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 inductance will be
(A) 3 mH
(B) 12 mH
(C) 24 mH
(D) 48 mH

6. Which circuit element(s) will oppose the change in circuit current?
(A) Resistance only
(B) Inductance only
(C) Capacitance only
(D) Inductance and capacitance

7. Increasing the field or increasing the current will decrease the force on the conductor.
(A) Yes
(B) No

8. Which of the following inductor will have the least eddy current losses?
(A) Air core
(B) Laminated iron core
(C) Iron core
(D) Powdered iron core

9. In case all the flux from the current in coil 1 links with coil 2, the coefficient of coupling will be
(A) 2.0
(B) 1.0
(C) 0.5
(D) Zero

10. A laminated iron core has reduced eddy-current losses because
(A) More wire can be used with less D.C. resistance in coil
(B) The laminations are insulated from each other
(C) The magnetic flux is concentrated in the air gap of the core
(D) The laminations are stacked vertically

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