PH3202 Physics for Electrical Engineering Important Questions
Unit 1
1. Derive an expression for orientational polarization in dielectric materials. Discuss how it varies with the temperature of the dielectric material.
2. Obtain an expression for internal field within the dielectric material and derive the Clausius-Mossotti equation.
3. Derive expressions for Electronic Polarization and Ionic Polarization in a dielectric material,
4. Show how microscopic property of atomic polarizability is related to macroscopic dielectric constant by obtaining expressions for Lorentz internal field and Clausius-Mossotti equation.
5. Discuss the frequency dependence of polarization of dielectric materials.
6. Calculate the electronic polarizability of neon. Given radius of neon atom is 0.16 nm and permittivity of free space is 8.85 × 10-12 Fm-1.
7. Define local field and derive Claussius-Mossoti equation.
8. Compare the insulation breakdown in gases, liquids and solids.
Unit 2
- Derive expressions for density of energy states in a solid and obtain the Fermi Energy of electrons in a material at 0 Κ.
- Obtain an expression for paramagnetic susceptibility of a solid and explain the behavior of paramagnetic solid with variation in temperature.
- Derive expressions for density of energy states in a solid.
- Explain how electrons behave in a periodic potential in a solid.
- Classify magnetic materials and explain diamagnetic, Paramagnetic and Ferromagnetic effects.
- Based on classical theory, deduce the expression for electrical conductivity.
- Using the Fermi function, evaluate the temperature at which there is 1% probability that an electron in a solid will have an energy 0.5 eV above Ef of 5 eV.
- Discuss in detail the origin of band gap when the electron is moving in the periodic potential.
- What are GMR devices? List the applications of these.
Unit 3
- Derive expressions for density of electrons in an intrinsic semiconductor and from the results, obtain an expression for density of electrons in an n-type semiconductor.
- Derive expressions for Carrier transport by drift and diffusion of electrons and holes in semiconductors.
- Derive carrier concentration in an intrinsic semiconductor and from the results, obtain an expression for density of electrons an N-type semiconductor.
- Explain the variation of carrier concentration with temperature in a P-type semiconductor using suitable theory and diagram.
- Differentiate intrinsic and extrinsic semiconductors with examples.
- Deduce an expression for carrier concentration in intrinsic semiconductor.
- With neat diagram, explain the experiment to measure the concentration of charge carriers in N type semiconductor using Hall effect.
Unit 4
- Describe the optical processes in semiconductors with diagrams.
- Describe the construction and operation of an LED and Laser Diode.
- Give the classification of Optical materials and explain the different optical processes in semiconductors.
- Explain Electro-Optic Modulators and switching devices in detail.
- Tabulate various optical materials and its applications.
- Discuss the optical absorption in metals, semiconductors and insulators.
- Explain the construction, working and advantages of
(1) LED
(2) Laser diode
Unit 5
- Formulate expressions for Density of states for different dimensional quantum structures and explain its dependence on energy of the quantum structure.
- Explain the construction and working of Single Electron Transistor
- Explain the Single electron phenomena and the working of Single electron Transistor.
- Explain the properties and applications of Carbon nanotubes.
- Draw the schematic sketches and corresponding density of states of various low dimensional nanostructures.
- What are nanomaterials and how are they unique?
- What is Coulomb blockade effect? Explain its role in the working of Single electron transistors.
- Give a note on the synthesis techniques and characteristics of metallic nano wires.