B.Sc.(part 2) Paper set of Physics Paper 3 Summer 2007

B.Sc.(part 2) Paper set of Physics Paper 3 Summer 2007

This is B.Sc.(part 2) Paper set of Physics Paper 3 Summer 2007

B.Sc. (Part 2) Examination
Physics
Paper 3

(Geometrical and Physical Optics)

Time—Three hours] [Maximum marks—40

N.B. :-- (1) All questions are compulsory.
(2) Draw neat diagrams wherever necessary.

EITHER

1. (A) (1) What is fermats Principle ? (1 mark)
(2) Explain Rectilinear Propagation of light on the
basis of formats principle. (2 mark)
(3) Deduce the Lens formula

1/f = (µ -1) [ 1 / R1 – 1 / R2 ] (3 mark)

(4) Find the Focal Length of a Plano convex lens
of radius of curvature 30 cm and µ = 1.50.
OR

1. (B) (1) What is eyepiece? ( 1 mark)
(2) How is multiple lens eyepiece better than single
lens eyepiece ? (2 mark)
(3) Explain the construction of Ramsden’s eyepiece,
with a neat diagram. (2 mark)
(4) For Ramsden’s eyepiece, find:
(a) Focal length of equivalent lens and
(b) Position of principal point. (3 mark)



EITHER

2. (A) (1) State and explain Rayleigh’s criterion for
resolution. (2 mark)
(2) Derive an expression for the resolving power
of telescope. (4 mark)
(3) Two point on the moon are resolved by a
500 cm telescope by using light of wavelength
5500 Å. The distance of the moon is 3.8 × 105 km.
from the earth. Find:
(a) the resolving power of telescope and
(b) Separation of two points on the moon. (2 mark)

OR

2. (B) (1) What is double reaction in uni-axial crystal? (1 mark) (2) Give Huygen’s general explanation of double
refraction in uniaxial crystals. (3 mark)
(3) Show that when planet polarized light falls normally
on a calcite crystal, with its faces cut along the
optic axis, it get converted into elliptically
polarised light. (4 mark)


EITHER

3. (A) Define aberration in lenses. What are the types and
subtypes of aberration? (2 mark)
(B) Explain the formation of circular fringes in Michelson
Interferometer. (2 mark)
(C) An oil immersion microscope resolve two time lines
Separated by a distance 2.54 × 10-5 cm. Using light
of wavelength 4000 Å , calculate the numerical
Aperture. (2 mark)

(D) A grating has 1250 lines per cm and second order
Maximum is obtained at Ө=30º Calculate the
wavelength of light used. (2 mark)


OR

3. (E) Two thin convex lenses of focsl length 12cm and
6cm are placed co-axially 8cm apart. Determine
the focal length of equivalent lens. (2 mark)

(F) Derive an equation for path-difference when
monochromatic light of wavelength (λ) is reflected
from a thin film of thickness ‘t’ and refractive
index ‘µ’. (2 mark)

(G) Explain the construction of fresnel’s half period zones
of plane wavefont. (2 mark)

(H) Calculate the minimum number of lines in a
Grating necessary to resolve the D1 and D2 lines of
Sodium of wavelengths 5890 Å and 5896 Å
respectively, in the first order. (2 mark)



EITHER

4. (A) Explain the construction of telephoto lens. (2 mark)

(B) A transparent film of glass of refractive index 1.5 is
introduce normally in the path of one of the interfering
beams of an interferometer which is illuminated by
light of wavelength 4800 A.U. The frings shift by
500 fringes. Determine the thickness of the film. (2 mark)
(C) With the help of neat diagram, explain the
Construction of Fabry-Perot interferometer. (2 mark)
(D) Derive an expression for the angle of rotation of the
Plan of polarisation, when a plane polarised beam
Of light pass through an optically active crystal of
Thickness d and refractive indices µl and µr . (2 mark)

OR

4. (E) Derive an Legrange’s equation for magnification.
(E) Explain the terms
(1) Entrance pupil and
(2) Exit pupil. (2 mark)
(F) Explain the different pattern obtain due to Fresnel
diffraction at a straight edge. (2 mark)
(G) calculate the maximum thickness of quarter-wave
plate of quartz for light of wavelength λ=6000Å.
Given µº= 1.553, µe = 1.544, for quartz. (2 mark)

5. (A) What is meniscus lens?
(B) Write down the condition of achromatism of two
lenses in contact.
(C) How can we obtain Newton’s ring with a bright
Centre?
(D) Draw a well-labelled diagram of rayleigh
Interferometer.
(E) Drow the intensity distribution curve of Fraunhofer
diffraction at a single site.
(F) What is Zone Plate?
(G) What happens when elliptically polarized light passes
through a quarter wave plate ?
(H) What os Lande’s ‘g’ factor? (1×8 mark)