Question
A room heater is rated 400 W, 220 V. If the supply voltage drops to 200 V, what will be the power consumed (approximately) ?
NEET
Physics
Current Electricity
2026
NEET 2026 (Cancelled)
NEET Physics Question (2026) — Solution
Options
- A. 200 W
- B. 400 W
- C. 331 W
- D. 121 W
Answer
C. 331 W
Step-by-step solution
The resistance of the room heater is given by R = V^2 P Substituting the rated values, R = 220^2 400 = 48400 400 = 121 When the supply voltage drops to V' = 200 V, the power consumed is P' = V'^2 R P' = 200^2 121 = 40000 121 330.57 W Therefore, the power consumed is approximately 331 W. Answer: 331 W
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