Question

A student connects a long air cored coil of magnanin wire to 100v d.c.supply and records a current of 25ampere.when the same coil is connected across 100v.50hz a.c.the current reduces to 20 ampere,the reactance of coil is

Answer 1

Answer : 3 ohm

Explanation:

For DC circuit:

R= 100÷25 = 4 ohm

For AC circuit:

Z = V÷I = 100÷20 = 5 ohm

Z=√(R^2 + Xl^2)

25=16 + Xl^2

Xl= 3 .