Question

An emf induced in a secondary coil is $10000V$ when the current breaks in the primary. The mutual inductance is $5H$ and the current reaches to zero in ${10}^{-4}$ s in primary. The maximum current in the primary before the break is

• A. $0.2A$
• B. $0.3A$
• C. $0.4A$
• D. $0.5A$

Answer 1

The correct option is A $0.2A$

$\varphi =Mi$
$emf=\frac{d\varphi }{dt}=M\frac{di}{dt}$
$10000=5\times \frac{i}{{10}^{-4}}$
$i=0.2A$