EN09 103 ENGINEERING PHYSICS1st Series Test

Time: 1 ½ Hr Max: 36marksSet- II

I. Short answer questions:

1. Explain spatial Coherence.2. Differentiate between Interference and Diffraction.3. What happens to the bandwidth in young’s double slit experiment if the distance between the

coherent sources is halved.

5 x 2 = 10 marks

II. Answer any two from the following:2 x 5 = 10 marks

4. Light of wavelength 6000Ǻ falls normally on a thin wedge shaped film of refractive index 1.4, forming fringes that are 2mm apart. Find the angle of the wedge.

5. What happens for the diameter of Newton’s ring if the apparatus is kept in liquid? Explain your answer.

6. Give diagram to show path difference in interference of light rays from thin film by reflection. Also give conditions for maxima and minima.

III. Answer the following: 2 x 10 = 20 marks

7. Explain how Newton’s rings are formed. Derive equations to calculate the wavelength and refractive index of the liquid using Newton’s rings.

OR8. Explain how fringes are formed in an air wedge. Derive equations to find the fringe width in air

wedge experiment.9. Explain young’s double slit experiment. Show that the fringe widths of dark and bright fringes

are same in the experiment.OR

10. How can you find the thickness of a transparent sheet of material using young’s double slit experiment? Also explain why we cannot use monochromatic light sources?