Question

A coil has an inductance of $0.7H$ and is joined in series with a resistance of $220\Omega$. When an alternating emf of $220V$ at $50cps$ is applied to it, then the wattless component of the current in the circuit is (take $0.7\pi =2.2)$

• A. $5A$
• B. $0.5A$
• C. $0.7A$
• D. $7A$

Answer 1

The correct option is B $0.5A$

wattless current = $I_{max}sin\left({tan}^{-1}\right\{L\omega /R\left\}\right)=\frac{220}{\sqrt{R^2+L^2{\omega }^2}}sin\left({tan}^{-1}\right\{L\omega /R\left\}\right)=0.5A$