Question

Coherent sources are characterized by the same:
A. Phase and phase velocity
B. Wavelength, amplitude and phase velocity
C. Wavelength, amplitude and frequency
D. Wavelength and phase

Answer 1

Hint:Laser light is an example of a light source that is coherent. The frequency and phase of the light produced by the laser are the same. Another example of a coherent source is sound waves. Sound waves generate electrical signals that propagate at the same frequency and phase.

Complete answer:
Two independent sources cannot be coherent because they aren't logical. The difference in phase between the two waves will not remain constant. The waves' wavelength and frequency would also be different. Also note that two identical and independent sodium lamps do not act as coherent sources because the phase difference between waves emitted will change randomly and sustained interference will not be possible.

We know that two wave sources are completely coherent if their frequency and waveform are similar and the phase difference between them is unchanged. When two waves have the same relative phase, they are said to be coherent. In simple words, two forces are said to be coherent sources, if their waves have the same frequency and constant phase difference.

Therefore, the correct answer is option C.

Note:We should remember that wavelength, amplitude and frequency are the coherent sources characteristics. Coherence is a wave property that allows for stationary interference. That is constant temporally and spatially.