JEE Main & Advanced Physics Wave Optics / तरंग प्रकाशिकी Important Terms

(1) Phase : The argument of sine or cosine in the expression for displacement of a wave is defined as the phase. For displacement \[y=a\sin \omega t;\] term \[\omega t=\] phase or instantaneous phase.

(2) Phase difference \[(\phi )\]: The difference between the phases of two waves at a point is called phase difference i.e. if \[{{y}_{1}}={{a}_{1}}\sin \,\omega \,t\] and \[{{y}_{2}}={{a}_{2}}\sin \,(\omega \,t+\varphi )\] so phase difference \[=\phi \]

(3) Path difference \[(\Delta )\]: The difference in path length?s of two waves meeting at a point is called path difference between the waves at that point. Also \[\Delta =\frac{\lambda }{\mathbf{2}\,\pi }\times \varphi \]

(4) Time difference (T.D.) : Time difference between the waves meeting at a point is \[T.D.=\frac{T}{\mathbf{2}\pi }\times \varphi \]