A $60 \mathrm{~W} / 120 \mathrm{~V}$ bulb is connected to a $240 \mathrm{~V} / 60 \mathrm{~Hz}$ supp

Question

A $60 \mathrm{~W} / 120 \mathrm{~V}$ bulb is connected to a $240 \mathrm{~V} / 60 \mathrm{~Hz}$ supply with an inductance in series. The value of inductance for the bulb to get correct voltage is,\

Professor PC Thomas Classes · Answer

$\mathrm{R}=\frac{(120)^{2}}{60}=240 \Omega$\ we require $\mathrm{i}=\frac{1}{2} \mathrm{~A}$ or $\mathrm{Z}=480 \Omega$\ $	herefore \mathrm{X}_{\mathrm{L}}=\sqrt{\mathrm{Z}^{2}-\mathrm{R}^{2}}$\ $=\sqrt{480^{2}-240^{2}}=240 \sqrt{3} \Omega$\ $\Rightarrow \mathrm{L}=\frac{\mathrm{X}_{\mathrm{L}}}{\omega}=\frac{240 \sqrt{3}}{60 	imes 2 \pi}$\