When electric bulbs of same power, but different marked voltage are connected in series across the power line, their brightness will be

Question

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

Tardigrade Admin · Accepted Answer

Resistance of bulb R=(V2/P), where V is the marked voltage and P is the marked power. P is same for both. As both bulbs are connected in series, so current in both of them will be same. So, brightness propto R propto V2.

Q. When electric bulbs of same power, but different marked voltage are connected in series across the power line, their brightness will be

proportional to their marked voltage

inversely proportional to their marked voltage

proportional to the square of their marked voltage

inversely proportional to the square of their marked voltage

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 connected in series, so current in both of them will be same. So, brightness $\propto R \propto V^{2}$ .

Q. When electric bulbs of same power, but different marked voltage are connected in series across the power line, their brightness will be

proportional to their marked voltage

inversely proportional to their marked voltage

proportional to the square of their marked voltage

inversely proportional to the square of their marked voltage

Resistance of bulb R=PV2​, where V is the marked voltage and P is the marked power. P is same for both. As both bulbs are connected in series, so current in both of them will be same. So, brightness ∝R∝V2.

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 connected in series, so current in both of them will be same. So, brightness $\propto R \propto V^{2}$ .