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Two bulbs of 220 V and 100 W are first connected in series and then in parallel with a supply of 220 V. Total power in both the cases will be ______.

Asked in RS Academy GUJCET booklet · Rated bulbs and appliances

• (1) 50 W, 100 W
• (2) 100 W, 50 W
• (3) 200 W, 150 W
• (4) 50 W, 200 W

Step-by-step solution

Why the other options are wrong

• (1) The series value is right, but the parallel value counts only one bulb. In parallel each bulb gets the full 220 V and runs at its rated 100 W, so the total is 200 W.
• (2) No single slip gives this pair. Sanity check: in series the resistance doubles, so the power falls to (220²)/(968) = 50 W; in parallel it halves, so the power is 200 W.
• (3) No single slip gives this pair. Sanity check: P = (V²)/(R_eq) with R_eq = 968 Ω (series) and 242 Ω (parallel) gives 50 W and 200 W.

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