Optics Answers

Fraunhofer diffraction is a special case of Fresnel diffraction. Explain. Also discuss the concept of Fresnel half-period elements.

Two coherent sources of light having intensity ratio 16:1 produce an interference fringe pattern. Calculate the ratio of the intensities of bright and dark fringes.

Two light waves propagating in the same direction are superposed. The frequency of the two light waves is the same and there is a constant phase difference between them. Obtain an expression for the intensity of the resultant wave.

What kind of polarised light will you get if two plane polarised light waves of equal amplitude but having a phase difference of 90º are superposed? Justify your answer. Explain why unpolarised light reflected by a pile of plates is linearly polarized.

Light waves are propagating in vacuum. Derive the wave equation for the associated magnetic field vector. On the basis of this equation, calculate the speed of light.

A diffraction grating has 2000 lines. Two sources of monochromatic lights emanating wavelengths λ1 and λ2 are just resolved by the grating in the first order spectrum. If the mean of λ1 and λ2 is 600 nm, calculate the difference between the wavelengths

A grating has 10,000 lines per cm. Calculate the maximum number of principal maxima that can be formed for light of wavelength 487 nm.

An extended source of light whose linear dimension is 0.3 mm is used in Young’s double slit experiment. Calculate the maximum separation between the slits for which interference pattern will be observable if the wavelength of light is 580 nm and separation between the source and the slits is 0.50 m.

The illustration shows a lamp and a candle illuminating a screen positioned between them. If the lamp is moved to a distance r = 1.02 m, how much brighter must the lightbulb be than the candle to have the same illuminance on the screen?

A diffraction grating has 2000 lines. Two sources of monochromatic lights emanating wavelengths λ1 and λ2 are just resolved by the grating in the first order spectrum. If the mean of λ1 and λ2 is 600 nm, calculate the difference between the wavelengths.