Roll No. …………………..
Lingaya’s University
B.Tech 1stYear (Term – III)
End Term Examination – May-June 2012
Applied Physics(PH - 102)
[Time: 3 Hours] [Max. Marks: 100]
Before answering the question, candidate should ensure that they have been supplied the correct and complete question paper. No complaint in this regard, will be entertained after examination.
Note: – Attempt five questions in all. All questions carry equal marks. Question no. 1 (Section A) is compulsory. Select four questions from Section B.
Section – A
Q-1.Part – A
Select the correct answer of the following multiple choice questions: [10×1=10]
(i)Atomic radius of BCC Lattice is
(a) (b)
(c) (d)
(ii)The Miller Indices of plane parallel to x-axis one
(a) (100)(b) (010)
(c) (001)(d) (111)
(iii)In a simple cubic Lattice d100 : d110 : d111 is
(a) 6 : 3 : 2(b) 2 : 3 : 6
(c) (d)
(iv)The phase velocity Vp and graph velocity Vgof de-Broglie wave in free space (speed of light c) are related as
(a) (b)
(c) (d)
(v)The KE of a particle confined in one dimensional box of length “L” is
(a) (b)
(c) (d)
(vi)The drift velocity Vd of electrons in a metal is related to electric field E and collision time τ as
(a) (b)
(c) (d)
(vii)Mobility is related to relaxation time as
(a) (b)
(c) (d)
(viii)Hall angle is expressed as
(a) (b)
(c) (d) None of these
(ix)Unit of Hall co-efficient is
(a) (b)
(c) (d)
(x)The Ratio of specific heats γ for manoatomic gas is equal to
(a)1.22(b) 1.44
(c)1.66(d) 1.88
Q-1.Part – B
(i)Define space Lattice, translation vector and co-ordination number give co-ordination no. of SC, BCC and FCC crystals. [5]
(ii)What do you mean by photoconductivity and derive the expression for current density? [5]
Section – B
Q-2.(a)Derive Bragg’s law for x-ray diffraction by a crystal. [8]
(b)Describe the powder method for the analysis of crystal structure. What are the advantages of this method? [12]
Q-3.(a)Discuss the difficulties with classical physics. [5]
(b)Derive the Plank’s radiation formula. Show that under limiting conditions the Wein’s law and Rayleigh Jean’s law can be derived from Plank’s radiation formula. [15]
Q-4.(a)What do you understand by effective mass of an electron? Prove that effective mass of an electron is given by relation
[10]
(b)What is Hall Effect? Derive the expression for Hall co-efficient, mobility and Hall angle. [10]
Q-5.(a)Show that the energy expression for an electron in one dimensional potential well is given by . [10]
(b)An electron is bound by potential which closely approaches to infinite square well of width 2.5×10-10 m. Calculate the lowest three permissible quantum energies the electron can have. [6]
(c)Calculate the longest wavelength that can be analyzed by rock salt crystal of spacing d = 2.82Å in the first order. [4]
Q-6.(a)State and prove principle of equipartition of energy. [8]
(b)What is Rankine cycle? Describe the processes involved in it. [12]
Q-7.(a)Discuss Langevin’s Theory of Paramagnetism and derive the expression for paramagnetic susceptibility. [15]
(b)Calculate Larmor’s frequency when an external magnetic field of 1 Tesla is applied to the material. [5]
Q-8.(a)Derive London’s Equation and discuss how its solution leads to Meissner effect. [10]
(b)Calculate the number density of electrons. Given the London Penetration depth is 529. [5]
(c)Distinguish between Hard and Soft superconductors? [5]
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