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

Asked in GSEB Board March 2019 · Rated bulbs and appliances

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

Step-by-step solution

Why the other options are wrong

• (1) 100 W for the parallel case counts only one bulb. In parallel both bulbs run at their full rated voltage, so the total is 2×100 = 200 W.
• (2) No single slip gives 50 W for parallel and 100 W for series. Sanity check: in parallel each bulb sees the full 220 V, so the parallel total (200 W) must be the larger one; series gives (220²)/(968) = 50 W.
• (4) These are the right values in the wrong order: 50 W, 200 W answers 'first series, then parallel'. The question takes parallel first.

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