A ray of monochromatic light is incident on the plane surface of separation between two media $$\mathrm{X}$$ and $$\mathrm{Y}$$ with angle of incidence '$$\mathrm{i}$$' in medium $\mathrm{X}$ and angle of refraction 'r' in medium Y. The given graph shows the relation between $$\sin \mathrm{i}$$ and $$\sin \mathrm{r}$$. If $$\mathrm{V}_{X}$$ and $$\mathrm{V}_{Y}$$ are the velocities of the ray in media X and Y respectively, then which of the following is true?

X-rays of wavelength $$\lambda$$ gets reflected from parallel planes of atoms in a crystal with spacing d between two planes as shown in the figure. If the two reflected beams interfere constructively, then the condition for maxima will be, (n is the order of interference fringe)

An interference pattern is obtained with two coherent sources of intensity ratio n : 1. The ratio $$\mathrm{{{{I_{\max }} - {I_{\min }}} \over {{I_{\max }} + {I_{\min }}}}}$$ will be maximum if

In a Young's double slit experiment, the intensity of light at a point on the screen where the path difference between the interfering waves is $$\lambda$$, ($$\lambda$$ being the wavelength of light used) is I. The intensity at a point where the path difference is $${\lambda \over 4}$$ will be (assume two waves have same amplitude)