If two light waves are coherent a) their amplitudes are the same their phase difference is constant their frequencies are the same b) c) d) their wavelengths are the san the difference in their frequencies is constant

a) their amplitudes are the same their phase difference is constant their frequencies are the same

Explanation:

Coherent waves are the waves that have constant phase difference, equal frequency, amplitude and waveform.

Frequency denotes the number of cycles a wave completes in one second.

Amplitude is the maximum height that the wave reaches.

Waveform is the two dimensional representation of a wave in graphical form.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.