Question

The average power dissipated in a pure inductor is

• A. $\frac{VI^{2}}{4}$
• B. $\frac{1}{2}VI$
• C. zero
• D. $VI^{2}$

Answer 1

Answer: (C)

zero

Answer 2

We know that in pure inductive circuit, current is lagging behind the voltage by $90^{\circ}$ i.e.
phase difference ( $\phi$ ) between voltage and current is $90^{\circ}$. Average power dissipated, $P _{ avg }=\frac{ v _{ o } i _{0}}{ 2 } \cos \phi$
$\therefore P _{ avg }=\frac{ v _{ o } i _{0}}{ 2 } \cos 90^{\circ}=0 \quad\left(\because \cos 90^{\circ}=0\right)$