Diffraction and interference of light demonstrate the ....... of light.

If two light waves reaching at a point produce destructive interference,then the condition of phase difference is:

Two light waves having the same wavelength $\lambda$ in vacuum are in phase initially. Then the first wave travels a path $L_{1}$ through a medium of refractive index $n_{1}$ while the second wave travels a path of length $L_{2}$ through a medium of refractive index $n_{2}$. After this the phase difference between the two waves is:

Two light waves of intensities $I$ and $4I$ superpose at a point with a phase difference of $\pi / 2$. Calculate the resultant amplitude at that point.

The light waves from two coherent sources have same intensity $I_{1} = I_{2} = I_{0}$. In the interference pattern,the intensity of light at minima is zero. What will be the intensity of light at maxima?

Two light rays having the same wavelength $\lambda$ in vacuum are in phase initially. Then the first ray travels a path $L_1$ through a medium of refractive index $\mu_1$,while the second ray travels a path of length $L_2$ through a medium of refractive index $\mu_2$. The two waves are then combined to observe interference. The phase difference between the two waves is