Rajasthan Technical University 2011-1st Sem B.Tech (Main/Back) ,- , Physics - I (Commto all Branches) - Question Paper
Roll No. : Total Printed Pages
B. Tech. (Sem. I) (Main/Back) Examination, January/February - 2011 Physics -1
(Common to all Branches of Engg.)
[Total Marks: 80 [Min. Passing Marks: 24
Time: 3 Hours]
Attempt overall five questions selecting: one question from each unit. All questions carry equal marks.
Use of following supporting material is permitted during examination. (Mentioned in form No. 205)
1.
Scientific Calculator
(Non-Proqrammable)
2.
Nil
(i) Explain the working of Michelsons interferometer. How it is used to measure the difference in the wavelength between the D lines of sodium light?
8
(ii) Michelson interferometer experiment is performed with a
O O
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?
4
(hi) Write short note on Interference filters.
4
OR
(i) Explain the formation of Newtons rings in reflected light. Why Newtons rings are circular in shape, Explain.
6
(ii) Light containing two wavelengths and X2 falls normally on a piano convex lens of radius of curvature R resting on a glass plate. If the 11th dark ring due to X1, coincides with
the (n+l)t h dark ring due to X2> prove that the radius of the
n,h dark ring of is jx1-X2'
6
(iii) Write short note on Anti-reflection coating.
' 4
(i) Show that plane polarised and circularly polarised light are the special cases of elliptically polarised light.
8
(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.
4
(iii) What is Malus Law?
4
OR
(i) Describe the construction and working of Laurents half shade polarimeter.
6
(ii) What are quarter wave and half wave plates? - Explain.
6
(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.
4
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Find out an expression for intensity at, a pomt, in the Fraunhofer diffraction due to a single slit. Draw the intensity distribution curve.
8
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.
4
What is difference in Fresnel's and Fraunhofer diffraction?
4
OR
Show that the intensity of light diffracted from a plane transmission grating is given by
j j. /'sina 'V f sin N$ |2 Where symbols have their usual meaning.
8
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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?
4
Explain Rayleigh criterion of resolution.
4
Obtain an expression for shift in wavelength of the scattered photon by Compton scattering
8
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.
4
Give physical interpretation of wave function.
. 4
OR
#
(i) Write down Schrodingers equation for a particle confined in a one dimensional box. Obtain the wave function for a particle confined in this box.
- 8
(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.
4
(iii) Explain normalized and orthogonal wave functions.
4
(i) State the postulates of special theory of relativity and deduce from them the Lorentz Transformations.
8
(ii) Rocket vV 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 ?
4
(iii) Describe experiment verification of time dilation.
4
OR
(i) Derive Einsteins mass energy relation and explain its importance.
6
(ii) Prove that particle having rest mass zero is always move with velocity of light.
6
(iii) If P and E represent the momentum and energy of a particle,
( e2)
P2
,2
V
then show that, under Lorentz Transformations,
* ,
is an invariant.
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