If two electric bulbs have $40\,W$ and $60\,W$ rating at $220\,V$, then the ratio of their resistances will be
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(a) $P = \frac{{{V^2}}}{R} \Rightarrow $ $\frac{{{R_1}}}{{{R_2}}} = \frac{{{P_2}}}{{{P_1}}} = \frac{{60}}{{40}} = \frac{3}{2}$
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