Related Mcqs:

1. The rate of rise of current through an inductive coil is maximum_____________?

   A. at 63.2% of its maximum steady value
   B. at the start of the current flow
   C. after one time constant
   D. near the final maximum value of current

2. When both the inductance and resistance of a coil are doubled the value of________________?

   A. time constant remains unchanged
   B. initial rate of rise of current is doubled
   C. final steady current is doubled
   D. time constant is halved

3. Energy stored by a coil is doubled when its current is increased by percent___________?

   A. 25
   B. 50
   C. 41.4
   D. 100

4. A ferrite core has less eddy current loss than an iron core because_______________?

   A. ferrites have high resistance
   B. ferrites are magnetic
   C. ferrites have low permeability
   D. ferrites have high hysteresis

5. Conductivity is analogous to____________?

   A. retentivity
   B. resistivity
   C. permeability
   D. inductance

6. Hard steel is suitable for making permanent magnets because_____________?

   A. it has good residual magnetism
   B. its hysteresis loop has large area
   C. its mechanical strength is high
   D. its mechanical strength is low

7. Those materials are well suited for making permanent magnets which have ________ retentivity and _________ coercivity

   A. low, high
   B. high, high
   C. high, low
   D. low, low

8. An air gap is usually inserted in magnetic circuits to____________?

   A. increase m.m.f.
   B. increase the flux
   C. prevent saturation
   D. none of the above

9. Those magnetic materials are best suited for making armature and transformer cores which have ________ permeability and ________ hystersis loss

   A. high, high
   B. low, high
   C. high, low
   D. low, low

10. If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be____________?

    A. zero
    B. small
    C. large
    D. none of the above