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JEE Main 2019 (12 Jan, Shift 1) · Electrical Power & Heating Effect

Electrical Power & Heating Effect question from JEE Main 2019 (12 Jan, Shift 1)

Q44JEE Main 2019 · 12 JAN · SHIFT 1Medium

Electrical Power & Heating Effect

Two electric bulbs, rated at (25 W, 220 V) and (100 W, 220 V), are connected in series across a 220 V voltage source. If the 25 W and 100 W bulbs draw powers P1 and P2 respectively, then:

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Answer: (b)

$R_1 = \frac{220^2}{25} = 1936\ \Omega$ , $R_2 = \frac{220^2}{100} = 484\ \Omega$ .
Series current $I = \frac{220}{1936 + 484} = \frac{1}{11}$ A.
$P_1 = I^2R_1 = \frac{1936}{121} = 16$ W, $P_2 = \frac{484}{121} = 4$ W.
So the answer is (b) $P_1 = 16$ W, $P_2 = 4$ W.

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