Question

In a coil current falls from 5 A to 0 A in 0.2 s. If an average emf of 150 V is induced, then the self inductance of the coil is

• A. 4 H
• B. 2 H
• C. 3 H
• D. 6 H

Answer 1

Answer: (D)

6 H

Answer 2

Here , $\frac{dI}{dt} = \frac{0 - 5}{0.2} = - 25As^{- 1},$

$\varepsilon = 150V$

As $|\varepsilon| = L\left| \frac{dI}{dt} \right|$

$\therefore L = \frac{|\varepsilon|}{|dI/dt|} = \frac{150}{25} = 6H$