LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – PHYSICS

SECOND SEMESTER – APRIL 2012

PH 2953 – ASTROPHYSICS

 

 

Date : 24-04-2012             Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

 

PART – A

Answer ALL questions:                                                                                                       (10×2=20)

1. What are the coordinates of the Altazimuth system and state its demerits?
2. Find the distance in a.u of a-canis majoris which has p = 0.²375 and m = -1.44.
3. Show F⁺_n = pB_n in an axissymmetric radiation from one hemisphere of a black body.
4. What is the significance of HR diagram?
5. How are binary stars classified?
6. State the causes of opacity in the stellar interior
7. Express Eddington’s mass-luminosity law. What is its defect?
8. What is meant by ZAMS?
9. What is a protostar?
10. Oultine the study of helioseismology.

 

PART – B

Answer any FOUR questions:                                                                                             (4×7.5 =30)

11. Describe the local equatorial system of coordinates for a star. Give the merits of the system.
12. Explain the method of determining the distance of stellar objects by cluster parallax method. Calculate the distance of Sirius B with magnitudes m = +8.6 and M = +11.4
13. Explain the following i) Russel-Vogt theorem ii) Modified Kramer’s law of opacity.
14. Derive all the basic equations of stellar structure
15. Apply the Virial theorem to an isothermal gas sphere and hence deduce the condition for Schoenberg – Chandrasekar limit.

 

PART – C

Answer any FOUR questions:                                                                                             (4×12.5 =50)

16 a. How is the observed magnitude of a star corrected for atmospheric extinction and color?  (8)

4. Show how Saha’s equation leads to the determination of T_ion for stars in thermodynamic equilibrium (4.5)

17 a.Apply Planck’s law of radiation to obtain an expression for the relative spectro-photometric gradient (Df) of two stars at temperatures T₁ and T₂ respectively               (7)

5. Discuss the relationships between stellar parameters for main sequence stars. (5.5)
6. Obtain expressions for the gravitational time scale both for convective and radiative equilibrium in the pre-main sequence contraction of stars. Draw the HR diagram and discuss the evolution of stars near the main sequence in star clusters.

19 a. Explain the neutrino problem.    (4)

8. Discuss the theories of nucleosynthesis to account for the abundance of elements in the Universe. (8.5)
9. Write notes on any TWO of the following.
10. i) Methods for determining the stellar radii ii) Jean’s criterion for star formation

iii) Post main sequence evolution of stars

 

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – PHYSICS

THIRD SEMESTER – NOVEMBER 2012

PH 3951 – CRYSTAL PHYSICS

 

 

Date : 08/11/2012            Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

PART – A

Answer ALL questions:                                                                                                                  (10×2=20)

1. List a few artificial methods of inducing nucleation.
2. Discuss the role of impurities in modifying the nucleation process.
3. Explain the mechanism of gelling.
4. Draw the apparatus for complex and de-complex method.
5. State the condition for growing crystals via hydrothermal approach.
6. Give examples for crystals grown by PVD.
7. Name a few modern versions of FT-RAMAN spectrometer.
8. Draw the experimental set-up for Kurtz-Perry SHG test.
9. Explain the procedure to determine the work hardening coefficient.
10. Mention the various kinds of polarization observed in a dielectric material.

 

PART – B

Answer any FOUR questions:                                                                                               (4×7.5=30)

11. With block diagram, discuss the functioning of a Differential Scanning Calorimeter (DSC).
12. Outline the growth of crystals by Bridgman method.
13. With suitable diagrams, explain the experimental procedure to grow crystals by chemical reaction methods employing the gel medium.
14. Discuss the procedure to determine the induction period by conductivity method.
15. With the block diagram explain the instrumentation and working of a FT-IR spectrometer.

 

PART – C

Answer any FOUR questions:                                                                                               (4×12.5=50)

16. Discuss the methodology to determine the various nucleation parameters with relevant theory and graphs.
17. Distinguish between the slow cooling and slow evaporation methods of growing crystals. With neat diagram explain the procedure for growing single crystals by low temperature solution growth along with various conditions to be optimized.                  (3.5+9)
18. List the advantages of growing crystals by melt method. Discuss the working principle involving the growth of crystal by Czochralski pulling technique. (3.5+9)
19. Explain the concept of photoconductivity. With the help of the circuit diagram discuss the procedure to measure the photoconductivity of a sample. (5+7.5)
20. Discuss the various types of hardness measurements.

 

 

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