MAGNETIC CIRCUIT QUIZ

When both the inductance and resistance of a coil are doubled the value of

Time constant is halved

Time constant remains unchanged

Initial rate of rise of current is doubled

Final steady current is doubled

TRUE ANSWER : ?
YOUR ANSWER : ?

The unit of retentivity is

Ampere turn/meter

Weber

Weber/sq. m

Ampere turns

TRUE ANSWER : ?
YOUR ANSWER : ?

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

Lowers their power efficiency

Leads to their increased weight

Produces fringing

Increases their cost of manufacture

TRUE ANSWER : ?
YOUR ANSWER : ?

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

Low, high

High, low

High, high

Low, low

TRUE ANSWER : ?
YOUR ANSWER : ?

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

70

50

500

20

TRUE ANSWER : ?
YOUR ANSWER : ?

The rate of rise of current through an inductive coil is maximum

At 63.2% of its maximum steady value

Near the final maximum value of current

At the start of the current flow

After one time constant

TRUE ANSWER : ?
YOUR ANSWER : ?

The relative permeability of a ferromagnetic material is

More than 10

More than one

More than 100 Ωr 1000

Less than one

TRUE ANSWER : ?
YOUR ANSWER : ?

The property of a material which opposes the creation of magnetic flux in it is known as

Reluctivity

Reluctance

Magneto-motive force

Permeance

TRUE ANSWER : ?
YOUR ANSWER : ?

Energy stored by a coil is doubled when its current is increased by percent.

41.4

42.5

47.5

44.6

TRUE ANSWER : ?
YOUR ANSWER : ?

A material for good magnetic memory should have

High retentivity

Low hysteresis loss

Low retentivity

High permeability

TRUE ANSWER : ?
YOUR ANSWER : ?

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