i. The property by which some doubly refracting crystals absorb the ordinary rays (O-rays) completely and extraordinary rays whose direction is parallel to the optic axis passing through the crystal, is called dichroism. ii. The crystal possessing dichroism property is […]
Tag: 12th std physics question and answers
Explain the applications of Doppler effect of light in astronomical physics.
i. Doppler effect of light is used to determine the radial velocities of distant galaxies. ii. It is used to measure the speed of rotation of the sun. a. The east and west edges of the sun are photographed. Each […]
Explain red and blue shift.
Red shift: When the source is receding away from the observer, then the frequency of light appears to be decreasing or the wavelength of light appears to be increasing to the observer. Therefore, the spectral line gets displaced towards red […]
What is a polaroid?
A large sheet of synthetic material packed with tiny crystals of a dichroic substance oriented parallel to one another so that it transmits light only in one direction of the electric vector is called a polaroid. […]
Define unpolarised light? Give its symbolic representation.
Unpolarised light: A light in which the vibrations of the electric vectors are in all possible directions, which are perpendicular to the directions of propagation is called as unpolarised light. Symbolic representation of unpolarised light is as shown in figure […]
Explain refraction of light on the basis of wave theory. Hence prove laws of refraction .
Laws of refraction Ratio of velocity of light in rarer medium to velocity of light in denser medium is a constant called refractive index of denser medium w.r.t. rarer medium. The incident rays, refracted rays and normal lie in the […]
State the main characteristics of wave normal & Wave front.
Characteristics of wave normal I. It gives the direction of propagation of wave. II. It is perpendicular to wave front. III. In a homogeneous isotropic medium, wave normal is same as direction of ray of light. IV. It is drawn […]