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A typical 60-W incandescent light bulb converts only 5 W of its electrical power into visible light. What happens to the remaining 55 W?
AIt is stored in the filament indefinitely
BIt dissipates into thermal energy instead
CIt returns to the electrical circuit unchanged
DIt converts into more light at another wavelength
Answer & Solution
Correct answer: B. It dissipates into thermal energy instead
1. The bulb draws 60 W of electrical power in total, but only 5 W of that is converted into visible light.
2. The remaining 55 W dissipates into thermal energy rather than becoming useful light output.
3. This waste heat is not stored indefinitely in the filament, nor is it sent back into the circuit unchanged, since energy delivered to the bulb is converted, not returned.
4. The wasted power does not reappear as more visible light at another wavelength; it is lost as heat, which is exactly why incandescent bulbs run hot.
_Source: OpenStax College Physics (CC BY 4.0), Ch 7 "Work, Energy, and Energy Resources", section 7.7 Power_
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