Engineering Physics - Dec 2014

First Year Engineering (Set B) (Semester 1)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.

Answer the any one question from Q1 & Q1 (e)

1 (a) What do you understand by wave function, discuss its physical significance?(2 marks) 1 (b) State and explain Heisenberg?s uncertainty principle. Explain diffraction of electron beam by a single slit to illustrate this principle.(2 marks) 1 (c) The uncertainty in measuring the speed of an accelerated electron is 1.2?10⁵ m/s. Calculate the uncertainty in finding its location, while it is still in motion. Given h=6.626?10^?34 Js and Mass of electron=9.31?10^?31 kg.(3 marks) 1 (d) What is meant by operators? Obtain an operator for the energy ?E?, momentum ?p? and use them to obtain Schrodinger wave equation.(7 marks) 1 (e) Define particle velocity, group velocity and phase velocity and derive the relation between them.(14 marks)

Answer the any one question from Q2 & Q2 (e)

2 (a) Explain the difference between interference and diffraction of light.(2 marks) 2 (b) State Brewster?s law and prove that at Brewster?s angle the reflected and refracted rays are perpendicular to each other.(2 marks) 2 (c) In Newton?s ring experiment the diameter of 15^th dark ring was found to be 0.59 cm and that of the 5^th ring was 0.336 cm. If the radius of curvature of plano-convex lens is 100 cm. Calculate the wavelength of light used.(3 marks) 2 (d) Explain the formation of Newton?s ring in reflected light. Prove that in reflected light [ D_n propto sqrt{n} and D_n propto sqrt{2n+1} ] where D_n and D'_n is diameter of dark and bright ring respectively.(7 marks) 2 (e) Discuss the phenomena of Fraunhofer diffraction at double slit. Derive the condition for maxima and minima for double slit diffraction pattern.(14 marks)

Answer the any one question from Q3 & Q3 (e)

3 (a) Why do we say that the nucleus behaves like a liquid drop?(2 marks) 3 (b) What do you understand by mass defect and binding energy with respect to the nucleus?(2 marks) 3 (c) The radius of Cyclotron dee's is 40 cm and magnetic field is 1.5 Wb/m². What is the maximum kinetic energy of beam of proton accelerated by the Cyclotron? Given mass of proton=1.67×10^-27 kg and Charge on Proton = 1.6×10^-19 C.(3 marks) 3 (d) Explain construction, principle of working and limitations of LINAC. In LINAC show that the length L_n of the n^th drift tube is proportional to √n.(7 marks) 3 (e) Discuss the construction and working of Cyclotron with neat diagram. Derive and explain resonance condition.(14 marks)

Answer the any one question from Q4 & Q4 (e)

4 (a) Superconductor is a perfect diamagnetic. Explain briefly.(2 marks) 4 (b) What is Zener breakdown. Explain briefly(2 marks) 4 (c) A n-type semiconductor specimen has Hall coefficient R_H=3.66×10^-4 m³/C. The conductivity of specimen is found to be 112 ohm^-1 m^-1. Calculate the charge carrier density and electron mobility at room tempertature.(3 marks) 4 (d) What is Hall effect? Deduce expression for Hall coefficient and Hall voltage of a solid. What important information's are obtained from its measurement?(7 marks) 4 (e) State and explain the terms dielectric polarization and Gauss's law. Derive the interrelationship between E, P and D vectors.(14 marks)

Answer the any one question from Q5 & Q5 (e)

5 (a) What is meant by stimulate emission? Explain the basic condition in which stimulated emission dominated.(2 marks) 5 (b) Differentiate between Step Index and Graded Index optical fiber cable.(2 marks) 5 (c) A glass clad fiber has cladding refractive index 1.49925 and fractional refractive index of 0.0005. Determine the critical internal reflection angle.(3 marks) 5 (d) Explain the construction and working of Ruby LASER with necessary energy level diagram.(7 marks) 5 (e) Describe the construction of an optical fiber. Explain the principle of propagation of light waves within a fiber. Define acceptance angle, acceptance cone and numerical aperture..(14 marks)