LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034                                   B.Sc. DEGREE EXAMINATION – PHYSICS

AC 09

FIFTH SEMESTER – NOV 2006

PH 5500 – ATOMIC & NUCLEAR PHYSICS

(Also equivalent to PHY 507)

 

 

Date & Time : 25-10-2006/9.00-12.00     Dept. No.                                                Max. : 100 Marks

 

 

 

PART – A

Answer ALL questions.                                                                     (10 x 2 = 20 Marks)

1. Define excitation potential and ionization potential of an atom.
2. What is Paschen-Back effect?
3. State Mosley’s law.
4. Describe how a photo-multiplier tube functions.
5. Explain parity of nuclei.
6. Define nuclear fission with example.
7. What is chain reaction?
8. What are pair production and annihilation?
9. What are cosmic rays?
10. Define range of alpha-particle.

PART – B

Answer any FOUR questions.                                                           (4 x 7.5 = 30 Marks)

11. a. Discus the normal Zeeman effect. (4.5)
12. Calculate the wavelength separation between the two component lines which

are observed in the normal Zeeman effect. The magnetic field used is 0.4    weber/m²;

the specific charge is 1.76×10¹¹ C kg^-1 and l = 6000 Å .        (3)

12. State and explain the laws of photoelectric effect.
13. Classify nuclei as isotopes, isobars, isotones, isomers, and mirror nuclei – Give examples.
14. Explain Bohn and Wheeler theory of nuclear fission and estimate the energy released when a neutron breaks into proton and electron.
15. Explain the latitude, East-West, and altitude effect of cosmic rays.

 

PART – C

Answer any FOUR questions.                                                           (4 x 12.5 = 50 Marks)

16. a. Describe the construction of Aston’s Mass Spectrograph with necessary theory

and show how it can be used in the detection of isotopes.                (8+4.5)

1. What are the advantages and limitations of Aston’s Mass Spectrograph? (p.54)
2. a. Derive Einstein’s photo-electric equation and describe Millikan’s experiment, with theory, to verify the same.
3. The photoelectric threshold for a metal is 3000 Å. Find the kinetic energy of an electron ejected from it by radiation of wavelength 1200 Å.

(Given: h = 6.62×10^-34 Js and c=3×10⁸ ms^-1.)                          (9+3.5)

18. What is nuclear magneton? Describe Rabi’s method to determine nuclear magnetic

moment.

19. Explain proton-proton and carbon-nitrogen cycle of thermo nuclear fusion.
20. a. Explain shell model of the nucleus.
21. Calculate the atomic number of the most stable nucleus for a given mass number A.                                                                                                                              (8+4.5)

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