Question

The magnetic engery stored in an inductor of inductance 4μH carrying a current of 2 A is:

• A. 4μJ
• B. 4μJ
• C. 4mJ
• D. 8μJ

Answer 1

The Correct Option is D

To determine the magnetic energy stored in an inductor, we use the formula for the energy stored in an inductor:

\(E = \frac{1}{2} L I^2\)

Where:

• \(E\) is the energy in joules (J).
• \(L\) is the inductance in henrys (H).
• \(I\) is the current in amperes (A).

Given:

• Inductance \((L) = 4 \, \mu H = 4 \times 10^{-6} \, H\)
• Current \((I) = 2 \, A\)

Substitute the values into the formula:

\(E = \frac{1}{2} \times 4 \times 10^{-6} \times (2)^2\)

Calculate step-by-step:

1. Calculate \(I^2 = 2^2 = 4\).
2. Substitute \(L\) and \(I^2\) into the formula: \(E = \frac{1}{2} \times 4 \times 10^{-6} \times 4\).
3. Calculate the product: \(E = \frac{1}{2} \times 16 \times 10^{-6}\)
4. Calculate further: \(E = 8 \times 10^{-6} \, J = 8 \, \mu J\).

Thus, the magnetic energy stored in the inductor is 8μJ.

Conclusion: The correct answer is 8μJ.