Question

Current in a coil changes at the rate of 10 A/s. The induced emf is 120V. Find the inductance $ L $ of the coil.

• A. \( 12 \, \text{H} \)
• B. \( 10 \, \text{H} \)
• C. \( 15 \, \text{H} \)
• D. \( 18 \, \text{H} \)

Hint:

Remember that the induced emf in a coil is proportional to the rate of change of current and the inductance of the coil.

Answer 1

The Correct Option is A

We are given:
- The rate of change of current, \( \frac{dI}{dt} = 10 \, \text{A/s} \)
- The induced emf, \( \mathcal{E} = 120 \, \text{V} \)
From Faraday’s law of electromagnetic induction, the induced emf is related to the inductance of the coil by: \[ \mathcal{E} = L \frac{dI}{dt} \] Substitute the given values: \[ 120 = L \times 10 \] Solving for \( L \): \[ L = \frac{120}{10} = 12 \, \text{H} \]
Thus, the inductance of the coil is \( 12 \, \text{H} \).