A 40 W bulb is connected in series with a room heater. If now 40 W bulb is replaced by 100 W bulb, the heater output will__________
Correct answer: B. increase
- A. decrease
- B. increase
- C. remain same
- D. heater will burn out
Explanation
At the same rated voltage, a 100 W bulb has lower resistance than a 40 W bulb because R = V²/P. Replacing it lowers the series resistance, raises current, and increases the heater's I²R output.
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