Wave Propagation and Interference - Optical Physics - Physics Previous Year Questions

For normal incidence at an air-glass interface with \( \mu = 1.5 \) the fraction of energy reflected is given by

Two monochromatic waves having frequencies \(\omega\) and \(\omega + \Delta\omega\) (\(\Delta\omega << \omega\)) and corresponding wavelengths \(\lambda\) and \(\lambda - \Delta\lambda\) (\(\Delta\lambda << \lambda\)) of same polarization, traveling along x-axis are superimposed on each other. The phase velocity and group velocity of the resultant wave are respectively given by

Interference fringes are seen at an observation plane \(z=0\), by the superposition of two plane waves \(A_1 \exp[i(\vec{k}_1 \cdot \vec{r} - \omega t)]\) and \(A_2 \exp[i(\vec{k}_2 \cdot \vec{r} - \omega t)]\), where \(A_1\) and \(A_2\) are real amplitudes. The condition for interference maximum is

In an interference pattern formed by two coherent sources, the maximum and the minimum of the intensities are \( 9I_0 \) and \( I_0 \), respectively. The intensities of the individual waves are

In a Young’s double slit experiment using light, the apparatus has two slits of unequal widths. When only slit-1 is open, the maximum observed intensity on the screen is \(4I_0\). When only slit-2 is open, the maximum observed intensity is \(I_0\). When both the slits are open, an interference pattern appears on the screen. The ratio of the intensity of the principal maximum to that of the nearest minimum is ________.

Light is incident from a medium of refractive index \( n = 1.5 \) onto vacuum. The smallest angle of incidence for which the light is not transmitted into vacuum is ______ degrees. (up to two decimal places).

Young’s double slit experiment is performed using a beam of \(C_{60}\) (fullerene) molecules, each molecule being made up of 60 carbon atoms. When the slit separation is 50 nm, fringes are formed on a screen kept at a distance of 1 m from the slits. Now, the experiment is repeated with \(C_{70}\) molecules with a slit separation of 92.5 nm. The kinetic energies of both the beams are the same. The position of the \(4^{th}\) bright fringe for \(C_{60}\) will correspond to the \(n^{th}\) bright fringe for \(C_{70}\). What is the value of \(n\) (rounded off to the nearest integer) ?