1) An arc lamp requires a direct current of 10A at 80 V to function. If it is connected to a 220V (rms) , 50Hz AC supply, the series inductor needed for it to work is close to A) 80H B) 0.08H C) 0.044 H D) 0.065 H Answer: Option DExplanation:$V^{2}=V_{R}^{2}+V_L^2\Rightarrow 220^{2}=80^{2}+V_L^2$ Solving we get, $VL \approx 205 V$ $X_{L}=\frac{V_{L}}{I}=\frac{205}{10}=20.5$Ω = ω L $L=\frac{20.5}{2\pi \times50}=0.065 H$
