Applied physics important question's

APPLIED PHYSICS 

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UNIT – 1

 1. Describe and explain the phenomenon of interference of light. 

2. Discuss in detail interference of reflected light in thin films 

3. Explain how Newton’s rings are formed and describe the method for determination of wavelength of light with their use.

 4. What is diffraction. Discuss the Fraunhofer diffraction at a single slit. 

5. What is plane transmission grating? Give the theory of a plane diffraction grating. 

6. What is polarization? Explain the phenomenon of double refraction. 

7. Explain Newton’s rings experiment with a neat diagram and obtain the condition for dark and bright fringe diameters.

 8. Describe Fraunhofer diffraction due to double slit.             

UNIT – 2 

1.a) Explain population inversion and stimulated emission in producing laser. 

b) Describe the construction and working of He-Ne gas laser.

 2 What is laser action? Explain the following terms with their specific importance in laser action.

 (i) Optical pumping (ii) Population inversion (iii) Metastable state 

3. Explain the terms: Spontaneous emission, stimulated emission and population inversion

. 4. Write a short note on Principle of Light amplification. 

5. Explain stimulated emission with a neat diagram. Describe the working principle of a He-Ne gas laser. 

6. Differentiate between spontaneous and stimulated emission. Give essential features of a LASER.

 7. Explain population inversion. Why is it necessary for laser action? What is meant by optical pumping?

 8. Describe the construction and working of a He-Ne gas laser. What are its merits and demerits?

 9. What does ‘LASER’ stand for? What are the essential features of it? 

10. Why the combination of He and Ne has been considered as the suitable choice to construct He-Ne laser? Explain it with energy level diagram. Explain the difficulty if only He or only Ne is used to obtain laser. 

10. Explain the principle of LASER and the importance of metastable states and optical pumping in achieving population inversion. 

11. With neat energy level diagrams for Nd-YAG laser, describe how a Nd-YAG LASER works. 

12. Explain the principle of optical fiber? 

13. Explain the following terms. a) Acceptance angle b) Numerical Aperture 14. Explain how optical fibers are classified?

 UNIT – 3 

1. Explain the following: 

i. Electric Polarization ii. Polarization vector iii. Electric displacement and iv. Polarizability. 

2. What is meant by polarization mechanism in dielectrics? Discuss different polarization mechanisms in dielectrics. 

3. What is ionic polarization? Derive an expression for ionic polarizability.

 4. What is local field in a dielectric material? Derive an expression for it by Lorentz method.

 5. Derive Clausius-Mosotti equation.

 6. Write short notes on Ferro-electricity and piezo-electricity. 

7. Explain the terms: i. Magnetic induction, ii. Magnetic susceptibility, iii. Permeability of a medium iv. Intensity of Magnetization. 

8. a) Discuss ferroelectricity in dielectric materials. (b) What are the differences between soft and hard magnetic materials? 

9. Draw and explain hysteresis curve for a ferromagnetic material placed in a magnetic field.

 UNIT – 4 

1. An electron is confined to a one-dimensional potential box of 2Å length. Calculate the energies corresponding to the second and fourth quantum states in eV. 

2. What are the salient features of quantum free electron theory? Mention its drawbacks. 

3. (a) Explain the difference between a matter wave and an electromagnetic wave.

 (b) Discuss the origin of electrical resistance in metals. 

4. Explain the concept of dual nature of the light. 

5. Explain the properties of matter waves. 

UNIT – 5 

1. Distinguish between intrinsic and extrinsic semiconductors. 

2. Derive an expression for the carrier concentration of an intrinsic semiconductor. 

3. Derive an expression for carrier concentration of p-type semiconductors. Explain the variation of Fermi level with temperature in the case of p-type semiconductors.

 4. Derive an expression for carrier concentration of n-.type semiconductors. Explain the variation of Fermi level with temperature in the case of n-type semiconductors

 5. Write notes on direct band gap and indirect band gap semiconductors. 

6. Explain Hall effect and its importance.

 7. Distinguish between type-1 and type-2 superconductors. 

8. Write a short note on BCS theory.

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