The distance between the first and the sixth bright fringes formed in Young’s double slit experiment (measured by a spectrometer) is found to be 12.5 mm. The separation between the slits is 0.12 mm and the distance of the screen from the slits is 60 cm. Calculate :

(i) the fringe width

(ii) the wavelength of the light used (in nm). 

(i) What is the difference between the electric field vector E at any point in the path of a linearly polarized light and that of an un-polarized light ?

(ii) Briefly describe how a given beam of light can be analysed and determined if it is linearly polarized or un-polarized.

A plano-convex lens made of glass (n = 1 5) has a focal length 10.0 cm.

(i) Calculate the radius of curvature of its curved surface.

(ii) If an identical plano-convex lens is placed in contact with the first (plane surfaces facing each other), what will be the power of the combination (in dioptres) ?

(i) State the three conditions for the formation of a pure spectrum.   

(ii) Draw the ray diagram illustrating the measurement of the angle of a prism using a spectrometer.

38. Draw the sketch of a simple model of a Bunsen’s grease spot photometer to compare the luminous intensity of two candles. Mention the formula used. 

The work function for sodium is 2.28 eV.    [3]

(i) What is the minimum energy for a quantum of radiation to cause photoelectric emission from a sodium surface ?

(ii) Calculate the wavelength of this radiation.