Part B important questions

I

1. Explain the basic principles involved in laser action.
2. Explain the working of He-Ne laser.
3. Explain the working of semiconductor diode laser.
4. With neat sketches explain in brief recording of a hologram and reconstruction of images. Mention the applications of holography.
5. Discuss the applications of lasers.
6. Obtain an expression for energy density of photons in terms of Einstein’s coefficients.

II

1. Using total internal reflection concept, obtain an expression for the acceptance angle and numerical aperture in an optical fibre.
2. What is attenuation in optical fibre? Explain the attenuation mechanisms.
3. Explain with block diagram optical fibre communication system.
4. Explain meissner effect and distinguish between type I and type II superconductors.
5. Explain BCS theory of superconductivity.
6. Discuss three applications of superconductivity.

III

1. Define lattice point, bravais lattice, unit cell and primitive cell.
2. Explain with neat sketch the diamond crystal.
3. Explain with neat sketch the NaCl crystal.
4. What are miller indices?
5. Obtain the expression for Bragg’s law.
6. Explain how Bragg’s spectrometer can be used to determine the interplanar spacing.

IV

1. Write a brief note on carbon nanotubes.
2. Write a brief note on fabrication technology of nanomaterials.
3. Write a brief note on nanomechanical bearings.
4. Describe a method of measuring the velocity of ultrasonic waves in solids.
5. Explain how an acoustic grating is used to determine the velocity of ultrasonic waves in liquid.
6. Explain ultrasonic method of non-destructive testing.