White light is passed through sodium vapours contained in a thin walled glass flask and the transmitted light is examined with the help of a spectrometer. The spectrum so obtained is :

When a beam of white light is passed through sodium vapours and then through a spectrometer, spectrum so obtained has two dark lines present in the yellow region. This spectrum is called :

When white light passes through a prism, the devination is maximum for

(a) When an unpolarized light of intensity I_(0) is passed through a polaroid , what is the intensity of the linearly polarized light ? Does it depend on the orintation of the polaroid ? Explain your answer. (b) A plane polarized beam of light is passed through a polaroid . Show graphically the variation of the intensity of the transmitted light with angle of rotation of the polaroid in complete one rotation.

An unpolarized light with intensity 2I_(0) is passed through a polaroid. The resultant intensity of the transmitted light will be

Light passes through a closed cylindrical tube containing a gas. If the gas is gradually pumped out, the speed of light inside the tube will

A ray of white light is passed through a glass prism and a spectrum is obtained on a screen. (a) Name the seven colours of the spectrum in order. (b) Do the colours have the same width in the spectrum ? (c) Which colour of the spectrum of white light deviates (i) the most, (ii) the least?

Draw a ray diagram showing the dispersion through a prism when a narrow beam of white light is incident on one of its refracting surface. Also indicate the order of the colours of the spectrum obtained.

Two polarising sheets have their polarising directions parallel to each other so that the intensity of transmitted light is maximum. The angle through wihich the either sheet must be turned so that intensity becomes one half the intial value is

Unpolarized light passes through two polaroids, the axis of one is vertical and that of the other is 30^@ to the vertical . What is the orientation and intensity of the transmitted light ?

Light from sodium lamp is made to pass through two polaroids placed one after the other in the path of light. Taking the intensity of the incident light as 100% , the intensity of the out coming light that can be varied in the range