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)

By energy stored in an inductor
$U=\frac{1}{2}L{i}_0^2$
($L=$ inductance of inductor, $i_0=$ current)
where $L=2H,i_0=1A$
$U=\frac{1}{2}\times 2\times 1^2=1J$