A material for good magnetic memory should have____________?

A. Low hysteresis loss
B. High permeability
C. Low retentivity
D. High retentivity

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

The initial rate of rise of current through a coil of inductance 10 H when suddenly connected to a D.C. supply of 200 V is__________Vs

A. 50
B. 20
C. 0.05
D. 500

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

Permanent magnets are normally made of_____________?

A. Alnico alloys
B. Aluminium
C. Cast iron
D. Wrought iron

The unit of magnetic flux is______________?

A. Henry
B. Weber
C. Ampereturn/weber
D. Ampere/metre

Point out the wrong statement. Magnetic leakage is undesirable in electric machines because it___________?

A. Lowers their power efficiency
B. Increases their cost of manufacture
C. Leads to their increased weight
D. Produces fringing

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

In a magnetic material hysteresis loss takes place primarily due to___________?

A. Rapid reversals of its magnetisation
B. Flux density lagging behind magnetising force
C. Molecular friction
D. It high retentivity

Hysteresis loss least depends on____________?

A. Volume of material
B. Frequency
C. Steinmetz coefficient of material
D. Ambient temperature