alleryHow does an incandescent bulb produce light?
ABy cooling a gas
BBy heating a filament
CBy bending sound
DBy stretching a magnet
Answer & Solution
Correct answer: B. By heating a filament
1. Currents cause Joule heating, which creates light in incandescent bulbs.
2. Cooling gas, sound waves and magnets are not the source.
3. So Joule heating is correct.
_Source: Wikipedia, Electric current, Lead section_
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