Question

In an ac circuit, the resistance of R $\Omega$ is connected in series with an inductance $I$. If phase angle between voltage and current be ${45}^{\circ }$, the value of inductive reactance will be:

• A. $R/2$
• B. $R/\sqrt{2}$
• C. $R$
• D. Insufficient data

Answer 1

Answer: (C)

$R$

$\frac{R}{\sqrt{R^2+X_L^2}}=cos\left(45\right)=\frac{1}{\sqrt{2}}\Rightarrow 2R^2=R^2+X_L^2\Rightarrow \left|X_L\right|=R$