LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – PHYSICS

CC 15

FIFTH SEMESTER – November 2008

PH 5500 – ATOMIC & NUCLEAR PHYSICS

 

Date : 03-11-08                        Dept. No.                                          Max. : 100 Marks

Time : 9:00 – 12:00

PART – A

Answer ALL questions:                                                                                            (10×2=20 Marks)

 

1. Why do the traces of parabola in Thomson’s method not pass through the origin?
2. State the advantages of Aston’s mass spectrograph.
3. The K_α line of molybdenum has a wavelength of 0.7078Å.Calculate the wavelength of the K_α line of copper. Atomic number of molybdenum is 42 and of copper is 29.
4. The photoelectric threshold for a metal is 3000Å. Find the kinetic energy of an electron ejected from it by radiation of wavelength 1200 Å.
5. What are isotones and isotopes?
6. Calculate the binding energy in MeV of deutrons. Given, mass of ₁H¹=1.008145amu,

mass of ₀n¹1.008987amu and mass of ₁H²=2.014741amu.

7. A reactor is developing energy at the rate of 32×10⁶ How many atoms of U²³⁵ undergo fission per sec? Assume that on the average an energy of 200 MeV is released per fission.
8. Distinguish between slow and fast neutrons.
9. What are cosmic rays?
10. What are particles and antiparticles? Give two examples.

 

PART – B

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

 

11. Explain the two types of coupling schemes between the orbital and spin angular momenta.
12. Explain the different types of photoelectric cells and their action.
13. a) Explain mass defect and binding energy.                (3)
14. b) Explain the variation of binding energy with mass number and discuss its salient

features.                                                                                                                                                              (4.5)

14. a) What do you mean by chain reaction?                                                                             (2.5)
15. b) Explain controlled and uncontrolled chain reaction.                                                                             (5)
16. a) Explain the main features of shell model of a nucleus.          (5)
17. b) What are magic numbers?                                                                                                                    (2.5)

PART – C

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

 

16. a) Describe Stern-Gerlach experiment. Discuss its significance.                        (10)
17. b) Why is an inhomogeneous magnetic field required in the experiment?                 (2.5)
18. a) Explain Millikan’s experimental verification of Einstein’s photoelectric equation.  (10)
19. b) Photon of energy 1.02MeV undergoes Compton scattering through 180°. Calculate the

wavelength of scattered photon.                                                                                                             (2.5)

18. a) Give the origin of β -ray line and continuous spectra.                                                                         (10)
19. b) Find out the stable nucleus that has a radius half of Fe⁵⁶.                                                                      (2.5)
20. Describe the construction and working of a nuclear reactor.
21. Discuss the latitude,altitude and east-west effects of cosmic rays. Plot the concerned

graphs.

 

 

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