Solapur University Qusetion Paper,2014 Question Paper,PHYSICS (New) (Paper – II) Optics and Laser,B.Sc. (Part – I) (Semester – I)



Solapur University Qusetion Paper
B.Sc. (Part – I) (Semester – I) Examination, 2014
PHYSICS (New) (Paper – II)
Optics and Laser
Day and Date : Saturday, 7-6-2014 Thursday, 8-11-2012 Max. Marks : 50
Time : 11.00 a.m. to 1.00 p.m. 10.30 p.m. to 12.30 p.m.
Instructions : i) All questions are compulsory.
ii) Figures to the right indicate full marks.
iii) Use of logarithmic table or nonprogrammable calculator is
allowed.
iv) Neat diagrams must be drawn, wherever necessary.
v) Answer to every new question must be written on a new page.
1. Select and write the most appropriate answer from given alternatives for each
sub-question. 10
i) By Fermat’s principle, the condition for the time t to be extremum is
a) 0 dx
dt ≠ b) 0 dx
dt < c) 0 dx
dt > d) 0 dx
dt =
ii) In Fraunhofer type diffraction, edge of an obstacle is illuminated by
a) spherical wavefront b) cylindrical wave front
c) plane wavefront d) elliptical wavefront
iii) The phenomenon of bending of light round the edges of an obstacle is called
a) reflection b) refraction c) diffraction d) polarisation
iv) In Ruby Laser, pumping type used is
a) electrical b) optical c) chemical d) thermal
v) Light rays incident near the rim or edge of the lens are called
a) marginal rays b) paraxial rays
c) co-axial rays d) non-axial rays
P.T.O.
Seat
No.
SLR-CN – 204 -2- 

vi) Fringe width X for interference of light in wedge shaped film is given by
a) λ θ b) λ
θ c) μθ
λ
2 d) λ
2μθ
vii) Path difference Δ for destructive type of interference is given by
a) nλ b) 2nλ c) (2n +1)λ d) 2 (2n 1) λ +
viii) Value of radius of curvature of a curved surface of the plano-convex lens
used in the formation of Newton’s Rings is
a) large b) small c) infinity d) zero
ix) Focal length of Huygen’s eye-piece is 21 cm, focal length of eye lens will be
a) 8 cm b) 10 cm c) 12 cm d) 14 cm
x) When 15000 lines per inch are ruled on the surface of a plane diffraction
grating’ for this grating, grating element d is given by _________ cm.
a) 15000
1 b) 15000 c) 15000
2.54 d) 2.54
15000
2. Answer any five of the following. 10
i) Describe the Fresnel’s type diffraction of light.
ii) State any one application of : optical bench.
iii) Define : pumping process in connection with production of Laser.
iv) Write the condition of constructive type interference of light for the interference
of light in parallel faced film.
v) Explain the process of spontaneous emission of radiation.
vi) Calculate, the focal length of Ramsden’s eye-piece when focal length of eye
lens is 16 cm.
3. A) Answer any two of the following : 6
i) Describe any three properties of a Laser source of light.
ii) Write a short note on : Huygen’s Eye-Piece.
iii) How many of maximum orders will be visible if wavelength used is 6000 Å
and plane diffraction grating having grating element d = 1.693 × 10–4 cm ?
B) How are the replica of the original plane diffraction grating prepared ? 4
4. Answer any two of the following : 10
i) Explain construction and working of : Helium-Neon Laser.
ii) Describe the Ramsden’s Eye-Piece.
iii) Determine value of grating element of plane diffraction grating which is used.
For normal incidence of light a red coloured spectral line of wavelength 7000 Å
of a certain order coincides with a green coloured spectral line of wavelength
5250 Å of the next order at an angle of diffraction of 30°.
5. Answer any one of the following : 10
i) Describe an experiment of Newton’s Rings. Derive a formula for determining
the wavelength of monochromatic source of light by an experiment of Newton’s
Rings.
ii) Derive the condition of achromatism for two lenses kept in contact.
Calculate the focal lengths of two lenses used for formation of an achromatic
combination of focal length 150 cm. The lenses are kept in contact and
dispersive powers of their materials are : 0.018 and 0.027.

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