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(b) Two lamps, one rated 100 W; 220 V, and the other 60 W; 220 V, are connected inparallel to electric mains supply. Find the current drawn by two bulbs from the line,if the supply voltage is 220V |
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Answer» Resistance of 1st lamp, R1 = V1²/P1 = (220)²/100= 484 ohm Resistance of 2nd lamp, R2 = V2²/P2 = (220)²/60= 806.6 ohm Lamps are connected in parallel combination, Req = R1R2/(R1 + R2)= 484 × 806.6/(484 + 806.6)= 390394.4/1290.6= 302.5 ohm so, I = V/Req = 220/(302.5)=.72 Amp |
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