Practice MCQ Questions and answers on Physics-GK

Atmospheric refraction is the reason behind the twinkling of stars. The starlight on entering earth surface undergoes refraction continuously before it reaches to earth. The starlight bend towards the normal as it enters from rarer to denser medium. The air near the earth surface is denser than upper layers. Therefore the apparent position of the stars are slightly different from its actual position, when it is viewed from horizon. The apparent position of stars are not stationary and keeps on changing slightly, because the physical condition of the atmosphere are not stationary. Because of this the stars sometimes appears brighter and sometimes appear fainter.

The basic reason for the extraordinary sparkle of suitably cut diamond is that it has a very high refractive index.

Refractive Index of glass with respect to water is 9/8.

Red light suffers the least amount of deviation and violet the most. When a white light is made to pass through a prism, formation of a spectrum of seven colors occurs showing white light is a combination of seven separate colours.

The bending of light as it passes from one medium to another is called refraction. The angle and wavelength at which the light enters a substance and the density of that substance determine how much the light is refracted.

Absolute refractive index refers to a condition when light travels from vacuum to any other medium. As the absolute refractive index of a particular medium is supposed to be the refractive index of that medium in respect to the vacuum it will be the same for light as well. It will be greater than 1.

A lens is a transmissive optical device that focuses or disperses a light beam by the process of refraction.
Flint glass is used as an optical glass because it has relatively high refractive index and low Abbe number than other materials.

'Mirage' is an example of refraction and total internal reflection of light.

Mirage is due to unequal heating of different parts of the atmosphere.

The bending of light (i.e. refraction of light) as it moves from water to air makes the water tank appear to be less shallower than its real depth.