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. 24mh
D. 48mh

Which of the following is unit of inductance ?

A. Ohm
B. Henry
C. Ampere turns
D. Webers/metre

Which of the following circuit elements will oppose the change in circuit current ?

A. Capacitance
B. Inductance
C. Resistance
D. All of the above

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 vertfcally

The magnitude of the induced e.m.f. in a conductor depends on the______________?

A. Flux density of the magnetic field
B. Amount of flux cut
C. Amount of flux linkages
D. Rate of change of flux-linkages

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

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

The law that the induced e.m.f. and current always oppose the cause producing them is due to____________?

A. Faraday
B. Lenz
C. Newton
D. Coulomb

If current in a conductor increases then according to Lenz’s law self-induced voltage will____________?

A. Aid the increasing current
B. Tend to decrease the amount of cur-rent
C. Produce current opposite to the in-creasing current
D. Aid the applied voltage

Air-core coils are practically free from______________?

A. Hysteresis losses
B. Eddy current losses
C. Both (a) and (b)
D. None of the above