Current Electricity - Result Question 74
79. 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
[2004]
(a) $R / 2$
(b) $R$
(c) $2 R$
(d) $R / 4$
Show Answer
Answer:
Correct Answer: 79. (d)
Solution:
(d) $P=\frac{V^{2}}{R} \Rightarrow R=\frac{V^{2}}{P}=\frac{(220)^{2}}{60}=\frac{4(110)^{2}}{60}$
$R^{\prime}=\frac{(110)^{2}}{60}=\frac{R}{4}$
