LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – PHYSICS

FIFTH SEMESTER – APRIL 2006

                                                PH 5500 – ATOMIC & NUCLEAR PHYSICS

(Also equivalent to PHY 507)

 

 

Date & Time : 20-04-2006/AFTERNOON   Dept. No.                                                       Max. : 100 Marks

 

 

PART – A

 

Answer ALL the questions                                                             (10 ´ 2 = 20 marks)

1. State Pauli’s exclusion principle.
2. Distinguish between excitation and ionization potential of an atom.
3. A photon recoils back after striking an electron at rest. What is the change in the wavelength of the photon?
4. Find the minimum wavelength of x – rays produced by an x – ray tube operating at 1000 kV.
5. Define range and stopping power of a – particles.
6. Calculate the energy equivalent of 1 atomic mass unit.
7. Distinguish between nuclear fission and fusion.
8. What are magic numbers?
9. What is pair production?
10. What are the fundamental interactions in nature?

PART – B

Answer any FOUR questions                                                         (4 ´ 7.5 = 30 marks)

11. What is Zeeman effect? Derive an expression for Zeeman shift.
12. a) Explain the origin of characteristic x – rays.           (4.5)
13. b) State Mosely’s law? What is its importance?       (3)
14. a) What are isobars and isotones? Give one example for each (4)
15. b) Calculate the binding energy and binding energy per nucleon of Ca⁴⁰

Given,              mass of 1 proton = 1.007825 amu.

mass of 1 neutron = 1.008665 amu

mass of  = 39.96259 amu                                                         (3.5)

14. How was the neutron discovered? Give an account of its production and detection.
15. Discuss Yukawa’s meson field theory.

PART – C

Answer any FOUR questions                                              (4 ´ 12.5 = 50 marks)

16. a) Describe Thomson’s parabola method to measure the specific charge of positive ions.                                                                                  (8.5)
17. b) In a Bainbridge mass spectrograph, singly ionized atoms of Ne²⁰ pass into the     deflection chamber with a velocity of 10⁵ m/s. If they are deflected by a magnetic field of flux density 0.08T, Calculate the radius of their path and where Ne²² ions would fall if they had the same initial velocity.                     (4)
18. a) Explain millikan’s experimental verification of Einstein’s photoelectric equation.
19. b)   The wavelength of photoelectric threshold of Tungsten is 2300 .  Determine the kinetic energy of electrons ejected from the surface by ultraviolet light of wavelength 1800 .
20. Give the origin of b – ray line and continuous Spectrum. Outline the theory of b – disintegration.
21. a) Derive the four factor formula for the thermal nuclear reactor. (8.5)
22. b) A reactor is developing energy at the rate of 3000 kW.  How many atoms of U²³⁵ undergo fission per/second?  How many kilograms of U²³⁵ would be used in 1000 hours of operation assuming that on an average an energy of 200 in eV is released per fission?                                                                                  (4)
23. Describe the ‘liquid drop model’ of the nucleus. How can the semi-emirical mass formula be derived from it?  Mention the use of this model.

 

 

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