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JEE Main201912 Jan 2019Morning ShiftPhysicsCurrent ElectricityActual

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 P 1 and P 2 respectively, then:

Options

  1. AP 1 = 4   W ,   P 2 = 16   W
  2. BP 1 = 9   W ,   P 2 = 16   W
  3. CP 1 = 16   W ,   P 2 = 9   W
  4. DP 1 = 16   W ,   P 2 = 4   W

Correct answer

D. P 1 = 16   W ,   P 2 = 4   W

Step-by-step solution

R 1 = V 2 P = 220 × 220 25 = 44 × 44 R 2 = 220 × 220 100 = 22 × 22 As resistance are in series current through them will be same. P 1 P 2 = i 2 R 1 i 2 R 2 = 44 × 44 22 × 22 = 4 1 Therefore, among the given options, the option matching is P 1 = 16   W ,   P 2 = 4   W

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