QUESTION BANK
Polarization
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2)
3)
4)
5)
6)
What is law of Malus
Explain the term pile of plates.
Define plane of polarization and plane of vibration.
Explain the phenomenon of double refraction on the basis of Huygen’s wave theory.
Explain principle construction and working of half wave plate
What is quarter wave plate? Deduce the expression for its thickness in terms of
refractive indices of the quartz crystal
7) What are retardation plates? What are their types? Obtain expression for their
thickness.
8) Explain the term Dichroism. What are Polaroid’s and how are the produced
EXAMPLES
1) A polarizer and analyzer are oriented so that the amount of transmitted light is
maximum.
Through what angle should either be turned so that the intensity of transmitted light is reduced to (i)
0.75 (ii)0.25 times the maximum intensity?
2) Polarizer and analyzer are set with their polarizing directions parallel to that the intensity of
transmitted light is maximum. Through what angle should either be turned.So that the intensity be
reduced to (i) ½ and (ii) 25% of the maximum intensity?
3) Two polarizing plates have polarizing directions parallel so as to transmit maximum intensity of light.
Through what angle must either plates be turned if the intensity of the transmitted beam is one third
the intensity of the incident beam.
4) Calculate the thickness of (i)Quarter wave plate,(ii)Half wave plate.
Given: μe =1.553, μo=1.544, λ=5000 A0.
5) A Plane polarized light beam of wavelength 6000 A0 is incident on a thin quartz plate.
calculate the minimum thickness of the plate for which the O and E rays will combine to produce plane
polarized light. Given: μe =1.544, μo=1.553.
6) A quarter wave plate of thickness 2.275x10-3cm is cut with its faces parallel to the optic axis.The
emergent beam of light is elliptically polarized. Find the wavelength of monochromatic light made
incident normally on the plate. Given: μe =1.592, μo=1.586
7)A 20cm long tube containing 48 c.c of sugar solution rotates the plane of polarization by11o.If the
specific rotation of sugar is 66o,calculate mass of sugar in the solution.
8) Calculate the specific rotation of sugar solution using the following data: length of tube containing
solution=25cm,volume of solution=10gm and angle of rotation=16o 15’.
Laser
1) Explain the terms
a) Spontaneous emission
b) Stimulated emission
c) Metastable state
d) Population inversion
e) Optical pumping
f) Stimulated absorption
g) Life Time
h) Electrical pumping
i) Optical cavity
2) Explain properties of LASER.
3) Explain construction and working of Ruby Laser
4) Explain construction and working of He-Ne laser.
5) With the help of energy band diagram explain construction and working of
semiconductor Laser.
6) Describe propagation mechanism of light wave in optical fibers.
7) What is Holography ? Explain the process of hologram recording and
reconstruction.
Semiconductor
1) Define
A) Valance band B) Conduction band c) Forbidden energy gap
2) Explain the classification of solid on the basis of conductors, semiconductors
and Insulator on the basis of energy band theory
3) Using Fermi Dirac probability function, derive an expression for the position of
Fermi Energy level in the intrinsic semiconductor.
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4) Derive an expression for conductivity in intrinsic and extrinsic Semiconductors
5) Draw the energy band diagram s of P-N junction diode in forward bias and
reverse bias conditions.
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6) Explain Hall Effect in semiconductors. Derive the equation of Hall voltage and
Hall coefficient.
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7) State merits and demerits of solar cell?
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8) Explain the construction and working of solar cell
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9)What is Fermi energy level ? explain the working of p-n junction diode on
the basis of Fermi energy level in forward bias and reverse biased mode.
EXAMPLES
1)Calculate the band gap energy in silicon given that it is transparent to radiation
of wavelength grater than 11000Ao.
2)Calculate the wavelength at which Germanium starts to absorb light. The
energy gap in Germanium is 0.7eV.
3)Calculate the conductivity of pure silicon at room temperature when the
concentration of carriers is 1.6x1010 per cm3.
Take μe=1500cm2/V-s and μh =5000cm2/V-s at room temperature.
4)Calculate the number of acceptors to be added to a Germanium sample to
obtain the resistivity of 10Ω-cm.
Given :μ=1700cm2/V-sec
5) The resistivity of copper wire of diameter 1.03mm is 6.51 ohm per 300m.The
concentration of free electrons in copper is 8.4x1028/m3. If the current is 2A,find
the mobility of free electrons.
6) Find the temperature at which there is 1.0% probability that a state at which an
energy 0.5ev above Fermi energy will be occupied.
7)A copper specimen having length 1 meter, width 1 cm and thickness 1mm is
conducting 1 ampere current along its length and is applied with a magnetic field
of 1 tesla along its thickness. It experiences hall effect and a hall voltage of 0.074
microvolt. appear along its width . calculate the Hall coefficient and mobility of
electrons in copper. Conductivity of copper is б=5.8x107(Ωm)-1.
8)A slab of copper 2.0 mm in thickness and 1.5cm wide is placed in a uniform
magnetic field with magnitude 0.40T.When a current of 75amp flows along the
length ,the voltage measured across the width is 0.81Μv.Determine the
concentration of mobile electrons in copper.
9)Calculate the mobility of charge carriers in a doped silicon whose conductivity is
100per Ω-m and the Hall coefficient is 3.6x10-4m3/coulomb.
Superconductivity
1) Explain the phenomenon of superconductivity.
2) State and explain Meissner effect. Hence show that susceptibility is negative in
superconducting state.
3) Differentiate between Type l and Type ll Superconductors, on the basis of their
response to the magnetic field and exhibition of the Meissner Effect. Suppose
your explanation with the figures.
4) Explain what is the significance of critical magnetic field and critical current
density for
superconductors.
5) Explain the following properties of Superconductors
a) Meissner effect
b) Critical current
c) Isotope effect
d) Type l and Type ll Superconductors
Physics of nanoparticles
1. Explain optical and electrical properties of nanoparticles
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2. Explain synthesis of nanoparticales by colloidal route.
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3.. Explain any seven applications of nanoparticles
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4. State any four methods used for synthesis of nano- particles and describe
any one method
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5. Explain chemical vapour deposition method for manufacturing nano
Particles
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