A) 2 : 5
B) 5 : 2
C) 3 : 4
D) 4 : 3
Correct Answer: A
Solution :
Resistance of bulb \[R=\frac{{{V}^{2}}}{p}\] As V is constant hence, \[R\propto \frac{1}{p}\] or \[\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{{{p}_{2}}}{{{p}_{1}}}\] Here, \[{{p}_{1}}=250\,W,\,{{p}_{2}}=100\,W\] \[\therefore \] \[\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{100}{250}=\frac{2}{5}\]
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