List of top Physics Questions on Interference

The condition for maxima in the interference of two waves \( A e^{i(\frac{k}{\sqrt{2}}(\sqrt{3}x + y) - \omega t)} \) and \( A e^{i(\frac{k}{\sqrt{2}}(x + \sqrt{3}y) - \omega t)} \) is given in terms of the wavelength \( \lambda \) and \( m \), an integer, by:

A thin film of alcohol is spread over a surface. When light from a tunable source is incident normally, the intensity of reflected light at the detector is maximum for \( \lambda = 640 \, \text{nm} \) and minimum for \( \lambda = 512 \, \text{nm} \. Taking the refractive index of alcohol to be \( 1.36 \) for both the given wavelengths, the minimum thickness of the film would be .......... nm (Round off to two decimal places).

An experiment with a Michelson interferometer is performed in vacuum using a laser of wavelength 610 nm. One beam passes through a glass cavity 1.3 cm long. When the cavity is filled with a medium of refractive index \( n \), 472 dark fringes move past a reference line. The speed of light is \( 3\times10^8 \) m/s. The value of \( n \) is: