Question

The coefficient of mutual induction between two coils is 4 H. If the current in the primary reduces from 5A to zero in 10${}^{-3}$ second then the induced emf in the secondary coil will be

• A. ${10}^4$ V
• B. $25\times {10}^3$ V
• C. $2\times {10}^4$ V
• D. $15\times {10}^3$ V

Answer 1

Answer: (C)

$2\times {10}^4$ V

emf = $-M\frac{dI}{dt}$
$=-4\frac{0-5}{{10}^{-3}}=2\times {10}^{4}V$