When electric bulbs of same power, but different marked voltage are connected in series across the power line, their brightness will be :
A
proportional to their marked voltage
B
inversely proportional to their marked voltage
C
proportional to the square of their marked voltage
D
inversely proportional to the square of their marked voltage
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C
proportional to the square of their marked voltage
c Resistance of bulb $R=\frac{V^{2}}{P}$, Where $V$ is the marked voltage and $P$ is the marked power $P$. is same for both As both bulbs are connceted in series, so current in both of them will be same. So Brightness $\propto R \propto V^{2}$
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