An electric bulb is marked 100 W, 230 V. If t | vedclass

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(C) Given: Rated power $P = 100\ W$,Rated voltage $V = 230\ V$.First,calculate the resistance $R$ of the bulb filament using the formula $P = \frac{V^

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$30000$

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(C) Given: Rated power $P = 100\ W$,Rated voltage $V = 230\ V$.First,calculate the resistance $R$ of the bulb filament using the formula $P = \frac{V^2}{R}$.$R = \frac{V^2}{P} = \frac{230^2}{100} = \frac{52900}{100} = 529\ \Omega$.When the supply voltage drops to $V' = 115\ V$,the power consumed $P'$ is given by $P' = \frac{V'^2}{R}$.The time $t = 20\ min = 20 	imes 60\ s = 1200\ s$.The heat energy produced $H$ is given by $H = P' 	imes t = \frac{V'^2}{R} 	imes t$.Substituting the values: $H = \frac{115^2}{529} 	imes 1200 = \frac{13225}{529} 	imes 1200$.Since $13225 / 529 = 25$,we get $H = 25 	imes 1200 = 30000\ J$.

An electric bulb is marked $100\ W, 230\ V$. If the supply voltage drops to $115\ V$,how much heat (in $J$) is produced by the bulb in $20\ min$?

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