In an inductor of inductance `L=100mH`, a current of `I=10A` is flowing. The energy stored in the inductor is

Options

A. 5 J
B. 10 J
C. 100 J
D. 1000 J

Explanation

To find the energy stored in an inductor, we can use the formula:

\[ U = \frac{1}{2} L I^2 \]

where:
- \( U \) is the energy stored in the inductor,
- \( L \) is the inductance of the inductor,
- \( I \) is the current flowing through the inductor.

### Step-by-Step Solution:

1. **Identify the values given in the problem:**
- Inductance \( L = 100 \, \text{mH} = 100 \times 10^{-3} \, \text{H} = 0.1 \, \text{H} \)
- Current \( I = 10 \, \text{A} \)

2. **Substitute the values into the energy formula:**
\[ U = \frac{1}{2} L I^2 \]
\[ U = \frac{1}{2} \times 0.1 \, \text{H} \times (10 \, \text{A})^2 \]

3. **Calculate \( I^2 \):**
\[ I^2 = (10 \, \text{A})^2 = 100 \, \text{A}^2 \]

4. **Now substitute \( I^2 \) back into the equation:**
\[ U = \frac{1}{2} \times 0.1 \, \text{H} \times 100 \, \text{A}^2 \]

5. **Perform the multiplication:**
\[ U = \frac{1}{2} \times 10 \, \text{H} \cdot \text{A}^2 = 5 \, \text{J} \]

6. **Conclusion:**
The energy stored in the inductor is \( 5 \, \text{J} \).

### Final Answer:
The energy stored in the inductor is **5 joules**.