A) 100 W lamp
B) 40 W lamp
C) Both will glow equally
D) It cannot be predicted
Correct Answer: B
Solution :
From Joules law, heat produced \[H={{i}^{2}}Rt=\frac{{{V}^{2}}}{R}\] where i is current, R the resistance, t the time and V the potential difference. Since, lamps are connected in series, current through them is same. \[\therefore \] \[R=\frac{{{V}^{2}}}{H}\] \[\Rightarrow \] \[{{R}_{40}}>{{R}_{100}}\]Rico and \[{{H}_{40}}>{{H}_{100}}\].
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