Question

A 400 mH coil of negligible resistance is connected to an AC circuit in which an effective current of 6 mA is flowing. Find out the voltage across the coil if the frequency is 1000 Hz.

Answer 1

Given info : A 400 mH coil of negligible resistance is connected to an AC circuit in which an effective current of 6 mA is flowing.

To find : The voltage across the coil if the frequency is 1000 Hz is...

solution : inductance of coil, L = 400 mH = 0.4 H

effective current through circuit , $I_{eff}$ = 6mA = 0.006 A

frequency of the coil, f = 1000 Hz

∴ angular frequency , ω = 2πf = 2 × 3.14 × 1000

= 6280 rad/s

now impedance, Z = inductive reactance , $X_L$ = ωL = 6280 × 0.4 H/s

now voltage = $I_{eff}Z$

= 0.006 × 6280 × 0.4

= 15.072 Volts ≈ 15 volts

Therefore the voltage across the coil is 15 volts.