MCQ
Two sources are called coherent if they produce waves:
- AOf equal wavelength.
- BOf equal velocity.
- CHaving same shape of wavefront.
- ✓Having a constant phase difference.
✓
Answer
Correct option: D.
Having a constant phase difference.
For light waves emitted by two sources of light to remain coherent, the initial phase difference between waves should remain constant in time. If the phase difference changes continuously or randomly with time, then the sources are incoherent.
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