A 100 W bulb and a 60 W bulb are designed for the same mains voltage. Compared with the 60 W bulb, the 100 W bulb has
Correct answer: B. a lower resistance and draws more current
- A. a higher resistance
- B. a lower resistance and draws more current
- C. the same resistance
- D. a lower current
Explanation
At a fixed voltage, power is V squared over R, so a higher power rating means a lower resistance and therefore a larger current. Students often assume more power means more resistance, which is only true when the current rather than the voltage is fixed. Connecting the two bulbs in series reverses their apparent brightness for exactly this reason.
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About Maximum Power Output
Maximum power output describes the condition in which a source with internal resistance delivers the greatest power to an external load. The topic uses P = I²R and related circuit equations to show that maximum power occurs when load resistance equals internal resistance. This differs from maximum efficiency, which occurs under a separate condition.
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