Physics - Current Electricity Question with Solution | TestHub

(Brightness)$\propto$(Consumed power) .....(i)

For series combination

$P_{\mathrm{c}\mathrm{o}\mathrm{n}\mathrm{s}\mathrm{u}\mathrm{m}\mathrm{e}\mathrm{d} }= i^{2}R$

$\therefore P_{\mathrm{c}\mathrm{o}\mathrm{n}\mathrm{s}\mathrm{u}\mathrm{m}\mathrm{e}\mathrm{d} }\propto R$......(ii)

Also, Rated Power

$P_{\mathrm{R}\mathrm{a}\mathrm{t}\mathrm{e}\mathrm{d} }= \frac{V^2}{R}$

$P_{\mathrm{R}\mathrm{a}\mathrm{t}\mathrm{e}\mathrm{d} }\propto \frac{1}{R}$.....(iii

From, (i), (ii) and (iii)

$\left(\mathrm{B}\mathrm{r}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t}\mathrm{n}\mathrm{e}\mathrm{s}\mathrm{s}\right)\propto \left(\frac{1}{P_{\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{e}\mathrm{d}}}\right)$

∴ 25 W bulb will glow brighter.