Applied Physics 2 - Dec 2013

First Year Engineering (Semester 2)

TOTAL MARKS: 60
TOTAL TIME: 2 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Use suitable data wherever required.
(4) Figures to the right indicate full marks.

Attempt any five:-

1 (a) Explain why an extensive thin film appears dark in reflected light? (3 marks) 1 (b) How will you increase the resolving power of a diffraction grating? (3 marks) 1 (c) Calculate the numerical aperture of a fibre with core index n₁ = 1.61 & cladding index n₂ = 1.55.(3 marks) 1 (d) What if the difference between spontaneous & stimulated emissions. (3 marks) 1 (e) An electron is bound by a potential which closely approaches an infinite square well of width 2.5Å m. Calculate the first lowest permissible energy for electron. (3 marks) 1 (f) Write any two applications of CRO.(3 marks) 1 (g) What is MAGLEV? (3 marks) 2 (a) What do you understand by anti-reflection coating? Derive conditions with proper diagram.(8 marks) 2 (b) What is N.A.? Consider multimode step under fibre with n₁ = 1.53 and n₂ = 1.50 and λ = 1μm. If the core radius = 50μm then calculate the normalised frequency of the fibre (V) and the number of guided mode.(7 marks) 3 (a) What is the difference between holography & photography? Discuss the construction & reconstruction of image in holography with neat diagram.(8 marks) 3 (b) Derive the condition for maxima and minima due to interference of light reflected from a thin film of uniform thickness.(7 marks) 4 (a) What is the highest order spectrum which can be seen with monochromatic light of wavelength 6000Å by means of a diffraction grating with 5000 lines/cm.(5 marks) 4 (b) Explain the Heisenberg's uncertainty principle.(5 marks) 4 (c) What are type I & type II superconductors? (5 marks) 5 (a) A plane diffraction grating just resolve two lines in the second order. Calculate the grating element if dλ = 6Å, λ = 6×10^-5cm and the width of the ruled surface is 2cm.(5 marks) 5 (b) Derive Schrodinger's time independent wave equation.(5 marks) 5 (c) Explain the working of SEM with a neat diagram.(5 marks) 6 (a) Find energy of neutrons in units of electronvolts where De-Broglie wavelength is 1Å.
Mass of neutron = 1.674 10^-27kg
Plank's constant = 6.620 10^-34J/sec.(5 marks) 6 (b) Write a short note on electrostatic focusing.(5 marks) 6 (c) What are carbon tubes and what are their properties.(5 marks)