# Q.When both the inductance and resistance of the coil are doubled the value of

• ATime constant remains unchanged
• BInitial rate of rise of current is doubled
• CFinal steady current is doubled
• DTime constant is halved
Correct Answer : (A)

Time constant remains unchanged

Hints :

When both the inductance and resistance of the coil are doubled the value of Time constant remains unchanged.

An air gap is usually inserted in magnetic circuits to

The relative permeability of a ferromagnetic material is