Question

A $40$ $mH$ coil carries a current of $8A$, the energy stored in the coil is

• A. $240$ $mJ$
• B. $280$ $mJ$
• C. $320$ $mJ$
• D. $360$ $mJ$

Answer 1

The correct option is C $320$ $mJ$

$U=\frac{1}{2}L{i}^2$
$=\frac{1}{2}\times 40\times {10}^{-3}\times 8^2$
$=\frac{640}{2}\times {10}^{-3}=320mJ$