A) The resistance of the filaments in both the bulbs are same
B) The resistance of filament in 40 W bulb is more than the resistance of 100 W bulb
C) The resistance of the filament in 100 W bulb is more than the resistance of 40 W bulb
D) None of the above
Correct Answer: B
Solution :
We know that, \[P=\frac{{{V}^{2}}}{R}\] \[\Rightarrow \] \[R=\frac{{{V}^{2}}}{P}\] \[\therefore \] \[{{R}_{1}}=\frac{V_{1}^{2}}{{{P}_{1}}}\] \[=\frac{{{(200)}^{2}}}{40}=1000\,\Omega \] and \[{{R}_{2}}=\frac{V_{2}^{2}}{{{p}_{2}}}=\frac{{{(200)}^{2}}}{100}=400\,\Omega \] So, the resistance of filament of bulb of 40 W is greater than that of 100W.
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