Hall Ticket No Question Paper Code: AHS006
INSTITUTE OF AERONAUTICAL ENGINEERING
(Autonomous)
B.Tech I Semester End Examinations (Supplementary) February, 2017
Regulation: IARE-R16
ENGINEERING PHYSICS
(Common to CSE|IT|ECE|EEE)
Time: 3 Hours Max Marks: 70
Answer ONE Question from each Unit
All Questions Carry Equal Marks
All parts of the question must be answered in one place only
UNIT I
1. Explain the phenomenon of electronic, ionic and orientation based on their polarization mechanism
with neat diagrams.
An elemental solid dielectric material has polarizability 7 10􀀀40Fm2. assuming the internal
field to be Lorentz field. Calculate the dielectric constant for the material if the material has
3 1028atoms/m3.
2. Classify magnetic materials into para, dia and ferro, based on alignment of their magnetic moments
and the temperature dependence of susceptibility.
Explain the origin of magnetic moment based on electron theory. What is Bohr magneton?
Obtain an expression for it.
UNIT II
3. Why is an indirect band gap semiconductor not used in the construction of a semiconductor
laser? Explain using an E-K diagram.
Describe the construction of semiconductor diode laser and explain its working with the help of
energy level diagram.
4. Give two examples of semiconductor materials used in the construction laser diodes. What is the
band gap of a semiconductor material emitting a laser of wavelength 405 nm?
Mention the important differences between spontaneous and stimulated emission. Identify the
active species/medium and the mechanism by which population inversion is achieved in the case
of Ruby, He-Ne and semiconductor lasers.
UNIT III
5. Explain how different characteristics of nanomaterial can be determined using transmission electron
microscopy. What different parameters can be found using this technique?
Discuss the effect of size reduction to nano scale on any four properties of a material.
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6. How to do the characterization of nanomaterial by XRD. Calculate the wavelength of X-rays
which produce a first order maximum at an angle of 22 in a crystal with interplanar distance of
1.5 .
Explain quantum confinement nature of the nano material that drastically changes its properties
compared to bulk materials.

UNIT IV
7. What is the meaning of Set up the Schrodinger's time independent wave equation.
Calculate the first three energy values for an electron bound in an infinite potential well of width
5 nm.
8. Obtain the Eigen energy values and Eigen energy functions for a particle bound in an infinite
potential well.
Calculate the de Broglie wavelengths of an electron and a neutron both traveling at a speed of

UNIT V
9. What is Hall effect? Why do semiconductors exhibit higher Hall coefficient than metals?
What is Fermi energy? Show that the Fermi level lies midway between the valence and conduction
band in an intrinsic semiconductor.
10. Write a note on direct and indirect bang gap semiconductors. Give two examples for each.
Explain why a direct band gap material is used for light emission?
Why does the resistance of a semiconductor decrease with increasing temperature? Estimate the
electrical conductivity of intrinsic silicon at 300 given that the electron and hole mobilities
are 0:15 m2/V s and 0.05 m2/V s. The intrinsic carrier concentration is 1:2 1016/m3
at 300 K.
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