Current Electricity

JEE Main level, numerical answer, medium

124 of 380

Question 124 of 380

An electrical bulb rated 220V,100W220V,100W, is connected in series with another bulb rated 220V220V, 60W60W. If the voltage across combination is 220V220V, the power consumed by the 100W100W bulb will be about _____ WW.

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Answer: 14

Electric power is given by P=V2RP=\dfrac{{V}^{2}}{R}, here, VV is voltage and RR is resistance.
Now, for each bulb, R1=V2P=2202100=484Ω{R}_{1}=\dfrac{{V}^{2}}{P}=\dfrac{{220}^{2}}{100}=484\Omega and R2=V2P=220260=484(106)Ω{R}_{2}=\dfrac{{V}^{2}}{P}=\dfrac{{220}^{2}}{60}=484\left(\dfrac{10}{6}\right)\Omega
Net current through the series combination is I=220484+484×106A=0.171AI=\dfrac{220}{484+484\times \dfrac{10}{6}}A=0.171A
Hence, the power consumed by the 100W100W bulb is P1=I2R1=14.06W{P}_{1}={I}^{2}{R}_{1}=14.06W

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