Q1: Two inductors, L₁ and L₂, are in parallel. L₁ has a value of 25 H and L₂ a value of 50 H. The parallel combination is in series with L₃, a 20 H coil. The entire combination is across an ac source of 60 V_rms at 300 kHz. The total rms current is

ANS:B - 870 mA

1. L1 parallel with L2, which is ( 25 micro * 50 micro)/( 25 micro + 50 micro) = 16.67 micro Henry.

2. L1 and L2 parallel value series with L3 which is ( 16.67 Micro + 20 Micro) = 36.67 micro Henry.

So now put into the formula,

I rms= Vrms / 2*pai *F*L.

= 60/( 2*pi*300K*36.67 micro).
=0.87 A.
= 870 mA.