In India electricity is supplied for domestic use at 220 V . It is supplied at 110 V in USA. If the

Question

In India electricity is supplied for domestic use at 220 V . It is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is $R$, the resistance of a 60 W bulb for use in USA will be\

Professor PC Thomas Classes · Answer

(c) : In India, $P_{I}=\frac{(220)^{2}}{R}$; In USA, $P_{U}=\frac{(110)^{2}}{R_{U}}$ As $P_{I}=P_{U} \Rightarrow \frac{(220)^{2}}{R}=\frac{(110)^{2}}{R_{U}} \Rightarrow R_{U}=\frac{R}{4}$\