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__________?

Related Mcqs:

1. 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

2. A coil of wire is arranged with its plane perpendicular to a uniform magnetic field o flux density B. when the radius of the coil increases from r1 to r2 in time Δt then what is the emf induced in the coil ?

   A. ωB/r22-r12/Δt
   B. ωB(r2-r1)2/Δt
   C. ωB(r22-r12)/Δt
   D. ωB(r22+r12)/Δt

3. 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

4. A small coil lies inside a large coil. The two coils are horizontal concentric and carry currents in opposite directions. The large coil will experience______________?

   A. A torque about horizontal axis
   B. A torque about vertical axis
   C. An upward force along the axis
   D. No resultant force

5. The self-inductance of the coil may be defined as equal to the e.m.f. induced in volts when the current in the circuit changes at the rate of unit Weber turns

   A. Yes
   B. No

6. In case all the flux from the current in coil 1 links with coil 2, the co-efficient of coupling will be____________?

   A. 2.0
   B. 1.0
   C. 0.5
   D. zero

7. An e.m.f. of 16 volts is induced in a coil of inductance 4H. The rate of change of current must be______________?

   A. 64 A/s
   B. 32 A/s
   C. 16 A/s
   D. 4 A/s

8. Current changing from 8 A to 12 A in one second induced 20 volts in a coil. The value of inductance is___________?

   A. 5 mH
   B. 10 mH
   C. 5 H
   D. 10 H

9. 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

10. The emf induced in a coil by a changing magnetic flux may have unit as______________?

    A. ms-1A
    B. ms-2A-1
    C. kgms2A-1
    D. kgm2s-1A-1