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Q. Bank PI I /I ,I I T.Y.B.Sc. Sem V
Q.1) In a metal, if the temperature is increased, then
resistivity---
a) Increases b) decreases c) remains same d) none of these
Q.2) The T > 0K probability of occupancy of Fermi level
is
a) 75% b) 90% c) 100% d) 50%
Q.3)The electron mobility in metals is given bya) v/V b) v/E c)
v/L d)
ne
Q.4) The Fermi factor for E = EFat any temperature is
a) 1 b) c) 0 d) 2
Q.5) If the mobility of electron in a metal increases, the
resistivity
a) Decreases b) Increases c) Remains constant d) none of
these.
Q.6) Ohms law relates to the electric field E, conductivity and
current density J
as a) J = E/ b) J = E2 c) J = /E d) J = E
Q.7) Experimentally specific heat at constant volume Cv is given
by
a) 3/2 R b) 10 -4RT c) 2/3 R d) 10 -4R
Q.8) The Fermi energy of a metal at absolute zero temperature is
proportional to
a) n1/3 b) n3/2 c) n2/3 d) n2
Q.9)At T> 0K, probability of occupancy of Fermi level isa)
75% b) 90% c ) 100% d) 50%
Q10) What is Fermi energy?
Q.11)Draw variation of Fermi factor with energy at
0otemperature.
Q.12)Draw variation of Fermi factor with energy at temperature
>0o.
Q.13) A superconductor will allow a magnetic field to penetrate
its interior.
Above statement is a) True OR b) Falls
Q.14) Draw resistivity against temperature graph for a
superconductor.
Q.15) If the Fermi energy of silver is 5.5 eV, the Fermi
velocity of conduction
electron is
a) 0.98 106m/s b) 1.39 106m/s c) 2.46 105 m/s d) None of
these
Q.16) Draw density of states Vs energy graph.
Q.17)State Bloch theorem.
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Q.18)Draw Energy Vs wave vector k graph.
Q.19) Draw effective mass Vs wave vector k graph.
Q.20)Write the value of momentum required for electron to escape
from surface in
thermionic emission.
Q.21)Term Cooper pair is refered to - a) electronproton b)
protron -protonc) neutronproton d a) electronelectron.
b.Write down the assumptions of classical free electron
theory.
c.Explain failure of classical free electron theory (06
Marks)
i) If the mobility of the electron is 7 10-3 m2/vs, when
accelerated by a field
1v/cm, the vd is given by
A) 7 10-3 m/s B) 0.7 m/s C) 7 10 -2 m/s D) 0.007 m/s
ii) The temperature dependence for electrical resistivity of
metal is
A) r 1/T B) r 1/T C) rT D) r T
d. Calculate the probability of an electron occupying an energy
level 0.02 eV
above the Fermi level at 200 K, in a material. (04 Marks)
ii) Mobility of electron is
A) Reciprocal of conductivity B) Flow of electrons per unitC)
Reciprocal of resistivity D) Average electron drift velocity per
unit electric
field
iii) If the mobility of electron in a metal increases, the
resistivity
A) decreases B)increases C) remains constant D) none of
these
iv) The dependence of mean free path on temperature T is
A) T B) T C) 1/ T D) 1/T (04 Marks)
