A circuit contains three resistances of 9Ω each and two inductors of 4 mH. Find the reading of ammeter when switch K is turned ON.
Solution:
When switch K is turned ON for a long time, inductors behave like short circuits.
Equivalent resistance:
R = 9Ω + (9Ω || 9Ω)
Parallel combination:
Rp = (9 × 9)/(9 + 9) = 81/18 = 4.5Ω
Total resistance:
R = 9 + 4.5 = 13.5Ω
Using Ohm’s law:
I = V/R
If supply voltage is 9 V:
I = 9/13.5 = 0.67 A
Answer: 0.67 A