• # question_answer The light waves from two independent monochromatic light sources are given by:  ${{y}_{1}}=2\,\sin \omega t$and ${{y}_{2}}=3\,\cos \omega t.$Then the correct statement is: A)  Both the waves are coherentB)  Both the waves are incoherentC)  Both the waves have different time periodsD)  None of the above

${{y}_{2}}=3\cos \omega t=3\sin \left( \frac{\pi }{2}+\omega t \right)$ So, the phase difference between them is $\frac{\pi }{2},$which remains constant with time, so they behave as coherent sources.                              Hence, the correction option is [a].