Punjab Technical University 2011-2nd 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) The speed of storing and studying out info from a computer core is less than a microsecond. Why it is necessary to use ferrite for this application?

b) describe spontaneous and stimulated emission.

c) discuss the term mode related to optical fibre.

d) Write the Maxwell equations in differential form.

e) Dose photon have mass? If no, then how photons have momenhrm?

f) What is the significance of Braggs law?

g) What is the significance of wave function?

h) elaborate the conditions for a material to be a superconductor?

i) How does x-rays differ from gamma rays?

j) What is the importance of uncertainty principle?

part – B [Marks : eight Each]

Q2) a) Write down Maxwell equations and discuss their significance.

b) A solenoid is one m long and three cm in diameter. It has 5 layers of windings of 850 turns every and carries a current of five A. What is B at its center.

Q3) a) discuss the term subsequent terms :
(i) magnetic anisotropy,
(ii) magnetostriction,
(iii) magnetic domains.

b) elaborate ferrite materials? provide a few of its useful applications.

Q4) a) Differentiate ranging from 3 level and 4 level lasers. provide the construction and working of He-Ne laser.

b) What is holography?

Q5) a) A fibre is made withcore of refractive index 1.5 and the cladding is doped to provide a refractive index difference of a 0.0005. obtain
(i) the cladding refractive index,
(ii) the critical angle,
(iii) acceptance angle and
(iv) numerical aperture.

b) define the role of fiber connectors, splicers and couplers in communication through optical fibers.

part – C [Marks : eight Each]

Q6) a) compute the mass and velocity of an electron having a total energy of 2MeV.

b) State the fundamental postulates of special theory of relativity and hence deduce the Lorentz transformation.

Q7) a) What thickness of lead will attenuate a beam of 0.4 MeV X-rays by a factor of 2? provided F= 2.3/cm.

b) Why X-rays are preferred for crystal structure determination? Derive an expression for Braggs legal regulations. How Braggs legal regulations is used in crystallography?

Q8) a) Derive an expression for the time dependent Schrodinger Wave formula.

b) What is the energy of gamma ray having a wavelength of IR.

Q9) a) discuss BCS theory of superconductivity.

b) elaborate London equations? obtain the expression for the penetration depth of a superconductor.

Earning:   Approval pending.