Applied Physics 2 - Dec 2011

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.

Answer any five from following:

1 (a) Explain the conditions for sustained interference pattern of light.(3 marks) 1 (b) what do you mean by diffraction and state it types.(3 marks) 1 (c) Explain two types of light sources used in optical communication systems.(3 marks) 1 (d) why electron microscope is considered better than optical microscope(3 marks) 1 (e) Explain de-Broglie^' hypothesis.(3 marks) 1 (f) Define relative permeability and susceptibility. Write the relation between them.(3 marks) 1 (g) What do you mean by vacuum? What are various gauge used to measure vacuum?(3 marks) 2 (a) Obtain the condition for maxima & minima due to interference in a wedge-shaped film observed in reflected light. Derive the expression for fringe width.(8 marks) 2 (b) What is diffraction grating? What is advantage of increasing number of lines in a grating? In an experiment with grating, third order of spectral line of wavelength λ, coincides with the forth order spectral line of wavelength 4992Å. Calculate the value of λ.(7 marks) 3 (a) What is De-Broglie concept of matter waves? Derive one dimensional time dependent Schrodinger equation for matter waves.(8 marks) 3 (b) Derive the expression for Numerical Aperture for a step index fibre. Calculate the acceptance angle for the fibre in water of refractive index 1.33 given that NA is 0.2 and cladding refractive index is 1.59.(7 marks) 4 (a) Obtain an expression for the radius of the n^th dark ring in case of Newton s rings. White light falls normally on a soap film of thickness 5 10^-5 cm and of refractive index 1.33 which wavelength in the visible region will be reflected more strongly.(8 marks) 4 (b) What is holography? Explain the process of recording & reconstruction of hologram.(7 marks) 5 (a) With neat energy level diagram explain the construction & working of He-Ne laser. What are its merits & demerits?(8 marks) 5 (b) Differentiate between soft and hard magnetic materials. In a magnetic material the field strength is found to be 10⁶ ampere/m. If the magnetic susceptibility of the material is 0.5x10^-5. Calculate the intensity of magnetization and the flux density in the material.(7 marks) 6 (a) Explain the atomic origin of ferromagnetism? Differentiate between diamagnetic and paramagnetic materials.(8 marks) 6 (b) Show that electron cannot pre-exist in Free State in nucleus. An electron has speed of 4 10^-5 m/s accurate to 0.01%. With what accuracy we can locate the position of electron?(7 marks)

Write short notes on:-

7 (a) AFM(3 marks) 7 (b) Rotary Pump(3 marks) 7 (c) Anti reflecting film(3 marks) 7 (d) Holography(3 marks)