BSc Physics SEM V 2018 19 2018-19 Physics II Solid State Physics Question Paper - Mumbai University | munotes

Questions asked in this paper

• (2) Figures to the right indicate full marks

1. Q1 (a) Attempt any one:
   • (i) the types of cubic crystal (SC) structures with neat diagram. 10 Find the distance between the nearest neighbours and atomic packing factor of FCC system
   • (ii) Derive the expression for drift velocity of free electrons in metals. 10 What are the drawbacks of classical theory for metals?
   • (b) Attempt any one:
   • (i) Define the terms: Coordination number, unit cell, basis, crystal 5 structure and single crystal
   • (11) Copper has fcc structure and its atomic radius is 0.1278nm. 5 Calculate its density. Take the atomic weight of copper as 63.5
2. Q2 (a) Attempt any one:
   • (i). Explain the Brillouin zones in one dimension and two dimensions 10 with neat diagram. How are they related to the energy levels of an electron in a metal?
   • (ii) Derive the expression for density of energy states in metals. 10
   • (b) Attempt any one: Derive the expression for the mean energy of electron gas at absolute 5 Show that the probability that a state AE above the Fermi level F; is 5 filled equals the probability that a state AE below is empty Paper Subject Code: 24126 Physics : Paper II - Solid State Physics. (R-2017)
3. Q3 (a) Attempt any one:
   • (i) Derive the expression for Fermi level and electron concentration in 10 n-type of semiconductor
   • (ii) Apply the continuity equation to find the expression for injected 10 minority carrier concentration in a bar of semiconductor subjected to radiation at one end as a function of distance under the state of
   • (b) Attempt any one:
   • (i) the expression for barrier potential at an open circuited P-N 5 junction in terms of dopping concentrations by using its energy band
   • (ii) In an intrinsic semiconductor with forbidden energy gap Eg= 0.7 eV, 5 determine the position of Fermi level at K if =6 me
4. Q4 (a) Attempt any one:
   • (i) down expression for reverse saturation current Io of a PN-diode 10 and discuss it for Ge and Si diodes. Derive the relation for temperature co-efficient of Ip which is defined as
   • (ii) What is diamagnetism? Derive the expression for the diamagnetic 10 susceptibility of a substance
   • (b) Attempt any one:
   • (i) Explain the Meissner effect in superconductors. 5
   • (ii) A Ge PN junction has reverse saturation current 1 at 5 Find its static and dynamic resistance for an applied bias of 0.3 V at
5. Q5 (a) Attempt any one:
   • (i) Draw the lattice planes (110), (231), (101) and (123). 4 Show that for simple cubic lattice = V6: V3: V2 4
   • (b) Attempt any one: the total number of energy states below FE = 5 eV ina 4 metal of volume m3. Assume the electrons to be free
   • (11) Estimate the electronic specific heat of copper at 300K. 4 for copper is Paper Subject Code: 24126 Physics : Paper II - Solid State Physics. (R-2017)
   • (c) Attempt any one:
   • (i) The Hall voltage for sodium metal is 0.001 mV measured at I= 100 4 mA, 2 Weber/ Thickness of specimen is 0.05 mm. Calculate the number of carriers per cubic meter in sodium
   • (ii) A germanium diode has donor atoms/m? in the n-region and 4 acceptor atoms/m? in the p-region. Find the value of barrier potential developed across the junction room temperature. Intrinsic carrier concentration for germanium is 2.15
   • (d) Attempt any one:
   • (i) A superconducting material has critical temperature of 4.5K in zero 3 magnetic field and critical field of 0.04 at 0 K. Find critical field at temperature 3 K
   • (ii) A magnetic material has magnetization of 3300 A/m and flux density 3 of 0.0044 Calculate the magnetizing force

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