Punjab Technical University 2010-2nd Sem B.Tech B Tech ester, , Physics , Regular , - Question Paper

Time: three Hours
Maximum Marks: 60

Instruction to Candidates:
1) Section- A is Compulsory.
2) Attempt any 5 ques. from Section- B & C
3) choose at lowest 2 ques. from part - B & C

part – A [Marks 2*10=20]

Q1)a) Which kind of magnetic materials have permanent magnetic dipole moment associated to them?

b) What is Bohr-magneton?

c) Which laser provide output radiation having frequency in the visible as well as IR region?

d) What does permittivity of a medium signifies. State its value fbr free space.

e) Why a 3 level laser normally give output?

f) What do you understand by10 five dB/Km@850nm?

g) I low you describe proper length and proper time interval as per special theory of relativity?

h) Why no state is not allowed for particle confined to an infinite potential box?

i) What is the physical significance attached to the conditions of continuity and single-valued nature of an acceptable wave function?

j) What is a Cooper pair?

part – B [Marks: eight Each]

Q2) (a) State and discuss the Amperes legal regulations and express it in differential form. Further discuss how Maxwell replaced this legal regulations to accept this as 1 of the Maxwell equations.

(b) The electrostatic potential in a certain space is provided by U=3x + four - y - 62. compute the corresponding electric field strength ( E).

Q3) (a) elaborate ferromagnetic domains? discuss their existence in terms of atomic dipole moments.

(b) How you distinguish ranging from hard and soft magnetic materials.

(c) What do you mean by magnetostriction?

Q4) (a) Specify 3 kinds of possible transitions ranging from 2 atomic energy levels and derive relations for the Einsteins coefficients.

(b) compute the ratio of transition rates of spontaneous emission to the stimulate deemission for light of wavelength1 0-6m and cavity temperature T=100K and hence determine which kind of emission will dominate?

Q5) (a) define construction of an optical fiber with help of diagram further, define various factors responsible for loss of signal propagating through a fiber.

(b) compute the numerical aperture acceptance angle and the critical angle of a fiber having core and cladding refractive indices as 1.5 and 1.45 respectively.

part – C [Marks: eight Each]

Q6) (a) State and discuss postulates of special theory of relativity with help of example.

(b) describe time dilation and derive the expression relating the time interval as observed in 2 inertial frames of references.

(c) obtain total energy of an electron and a proton, both having momentum equal to 2Me.

Q7) (a) What is Moseleys law? explain its significance.

(b) explain origin of characteristic and continuous x-rays.

(c) The 1st maxima for Braggs diffraction of x-rays from KCI crystal (d =0.314n m) appears at
14". compute energy of the incident x -rays.

Q8) (a) Establish time dependent Schrodinger wave formula and further deduct time independent form of this formula.

(b) What arc the characteristics of a well behaved wave-function.

(c) obtain the probability that a particle trapped in a box of width L can be obtained ranging from 0 .451 and 0 .55L for ground state.

Q9) (a) explain the important differences ranging from type-I and type-Il superconductors with help of example and plots of magnetization(M) Vs magnetic field (H).

(b) What is Meissner effect? Further discuss the effect of magnetic field on the superconducting state.

(c) describe London penetration depth and write its expression.

Earning:   Approval pending.