Why don't we see interference between two different light bulbs?
ALight bulbs emit different wavelengths
BThe light sources are not coherent. Their phase differences vary randomly and rapidly, washing out the pattern
CInterference does not exist for normal light
DBulbs are too far apart
Answer & Solution
Correct answer: B. The light sources are not coherent. Their phase differences vary randomly and rapidly, washing out the pattern
Ordinary light sources emit waves with random, rapidly changing phase relationships. Even if you could see momentary interference, it would shift faster than the eye can detect. Coherent sources (lasers, slits illuminated by same source) maintain stable phase relations.
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