Question

A solenoid of inductance $2H$ carries a current of $1A$. What is the magnetic energy stored in a solenoid ?

• A. 2 J
• B. 1 J
• C. 4 J
• D. 5 J

Answer 1

Answer: (B)

1 J

Answer 2

By energy stored in an inductor $U=\frac{1}{2} L i_{0}^{2}$ ($L=$ inductance of inductor, $i_{0}=$ current) where $L=2 H,\, i_{0}=1\, A$ $U=\frac{1}{2} \times 2 \times 1^{2}=1\, J$