Three equal resistors connected in series acr | vedclass

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(D) Let the resistance of each resistor be $R$ and the source $e.m.f.$ be $V$.In series connection,the equivalent resistance is $R_S = R + R + R = 3R$

Vedclass · Accepted Answer

$90$

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(D) Let the resistance of each resistor be $R$ and the source $e.m.f.$ be $V$.In series connection,the equivalent resistance is $R_S = R + R + R = 3R$.The power dissipated in series is $P_S = \frac{V^2}{R_S} = \frac{V^2}{3R} = 10 \ W$.From this,we get $\frac{V^2}{R} = 30 \ W$.In parallel connection,the equivalent resistance is $R_P = \frac{R}{3}$.The power dissipated in parallel is $P_P = \frac{V^2}{R_P} = \frac{V^2}{R/3} = 3 \left( \frac{V^2}{R} ight)$.Substituting the value $\frac{V^2}{R} = 30 \ W$,we get $P_P = 3 	imes 30 = 90 \ W$.

Three equal resistors connected in series across a source of $e.m.f.$ together dissipate $10 \ W$. If the same resistors are connected in parallel across the same $e.m.f.$,then the power dissipated will be .............. $W$.

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