Question

A coil of resistance 100 \( \Omega \) and inductance 5 H is connected to a 100 V battery. Then the energy stored in the coil is:

• A. 250 J
• B. 250 erg
• C. 125 J
• D. 125 erg

Hint:

The energy stored in an inductor is proportional to the square of the current.

Answer 1

The Correct Option is A

Step 1: Use the formula for energy stored in an inductor.
The energy stored in an inductor is given by: \[ E = \frac{1}{2} L I^2 \] where \( L \) is the inductance and \( I \) is the current.
Step 2: Calculate the current.
The current is given by: \[ I = \frac{V}{R} = \frac{100}{100} = 1 \, \text{A} \] Substituting the values into the energy formula, we get: \[ E = \frac{1}{2} \times 5 \times 1^2 = 2.5 \, \text{J} = 250 \, \text{J} \]
Final Answer: \[ \boxed{250 \, \text{J}} \]