alleryCoherent sources are those that emit waves of
ASame frequency AND a constant phase difference in time
BSame intensity only, without any relationship of frequencies
CSame wavelength only, regardless of the phase behaviour
DDifferent frequencies but a similar overall intensity level
Answer & Solution
Correct answer: A. Same frequency AND a constant phase difference in time
1. Sustained interference requires coherent sources.
2. Coherent sources emit waves with the same frequency (wavelength).
3. They must also maintain a constant phase difference over time.
4. Two independent light bulbs are not coherent; a laser output is.
_Source: syllabus Physics, Ch 10 "Wave Optics", §10.4_
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