JEE Main 2024 Physics question
When a coil is connected across a 20 V dc supply, it draws a current of 5 A. When it is connected across 20 V, 50 Hz ac supply, it draws a current of 4 A. The self inductance of the coil is mH. (Take π = 3)
Answer: 10
Solution
With dc, R = 20/5 = 4 Ω. With ac, Z = 20/4 = 5 Ω, so = √(25 − 16) = 3 Ω. L = /(2πf) = 3/(2 × 3 × 50) = 0.01 H = 10 mH.