Question

In a coil, the current changes form −2 A to +2 A in 0.2 s and induces an emf of 0.1 V. The selfinductance of the coil is ______.

Options

• 5 mH

• 1 mH

• 2.5 mH

• 4 mH

Answer 1

In a coil, the current changes form −2 A to +2 A in 0.2 s and induces an emf of 0.1 V. The selfinductance of the coil is 5 mH.

Explanation:

Given: Time (ΔT) = 0.2 s

Induced emf (E) = 0.1 V

Change in current (ΔI) = (+2) − (−2) = 4 A

By using the formula:

E = `L (Delta I)/(Delta T)`

0.1 = `L xx 4/0.2`

0.1 = L × 20

L = `0.1/20`

= 0.005 H

= 5 mH