# RTU Previous Question Papers BE 1st Semester

# Engineering Physics-1 July 2011

**UNIT – I**

1 (i) Explain the working of Michelson’s interferometer. How it is used to measure the difference in the wavelength between the D lines of sodium light?

(ii) Michelson interferometer experiment is performed with a source which have two wavelengths 4882 A and 4886 A. By what distance does the mirror have to be moved between positions of disappearance of fringes?

(i). Write short note on Interference filters.

**OR**

1. (i) Explain the formation of Newton’s rings in reflected light. Why Newton’s rings are circular in shape, Explain.

(ii) Light containing two wavelengths X_{l} and X_{2} &Us normally on a piano convex lens of radius of curvature R resting on a glass plate. If the n^{th} dark ring due to , coincides with the (n+l)^{th} dark ring due to X_{2}, prove that the radius of

(iii)Write short note on Anti-reflection coating.

**UNIT – II**

2 .(i) Show that plane polarised and circularly polarised light are the special cases of elliptically polarised light.

(ii) Intensity of light through a polariser and analyser is maximum when their principal planes are parallel. Through what angle the analyzer must be rotated so that the intensity gets reduced to 1/4 of the maximum value.

(ii) What is Malus Law?

**OR**

(i) Describe the construction and working of Laurent’s half shade polarimeter.

(ii) What are quarter wave and half wave plates? – Explain.

(iii) 80 gm of impure sugar when dissolved in a litre of water, gives an optical rotation of 9.9°, when placed in a tube of length 200 mm. If the specific rotation of sugar is 66 degree/dm / (gm/cc), find the percentage purity of sugar sample.

**UNIT – III**

3. (i) Find out an expression for intensity at a point in the Fraunhofer diffraction due to a single slit. Draw the intensity distribution curve.

(ii) The width of a slit is 0.012 mm. Monochromatic light is incident on it. The angular position of first bright line is 5.2°. Calculate the wavelength of incident light.

(iii) What is difference in Fresnel’s and Fraunhofer diffraction?

**OR**

(i) Show that the intensity of light diffracted from a plane transmission grating is given by Where symbols have their usual meaning.

(ii) A diffraction grating just resolves lines 4547.27 A and 4547.98 A in third order. Will it resolve lines 6437.48 A and 6437.95 A in the first order?

(iii) Explain Rayleigh criterion of resolution.

**UNIT – IV**

4. (i) Obtain an expression for shift in wavelength of the scattered photon by Compton scattering.

(ii) In compton experiment the wavelength of x-ray radiation scattered at an angle of 45° is 0.022 A. Calculate the wavelength of the incident x-rays.

(iii) Give physical interpretation of wave function.

**OR**

4. (i) Write down Schrodinger’s equation for a particle confined in a one dimensional box. Obtain the wave function for a particle confined in this box.

(ii) A particle is moving in one-dimensional potential box of infinite height) of width 25 A. Calculate the probability of finding the particle within an interval of 5 A at the centres of the box when it is in its state ot least energy.

(iii) Explain normalized and orthogonal wave functions.

**UNIT – V**

5. (i) State the postulates of special theory of relativity and deduce from them the Lorentz Transformations.

(ii) Rocket A’ travels towards the right and rocket ‘B^{!} travels to the left, with velocities 0.8 c and 0.6 c, respectively relative to the earth. What is the velocity of rocket A’ measured from rocket ‘B ?

(iii) Describe experiment verification of time dilation.

**OR**

(i) Derive Einstein’s mass energy relation and explain its importance.

(ii) Prove that particle having rest mass zero is always move with velocity of light.

(iii)If P and E represent the momentum and energy of a particle, then show that, under Lorentz Transformations, is an invariant.

I want a unit test paper

rtu physics paper

not bad

this type question should be required answer