Physics 124-final 2005

(B. Sc. Biochemistry) Second Semester 2005 Subject: Phys 124 (Physics II)

Full Marks: 100 Pass Marks: 45 Time: 3 hours

Candidates are required to give their answers in their own words as far as practicable. The figure in the margin indicates full marks. 1. 2. 3. 4.

Group (A) Long Questions (Any three) (3× ×14 = 42) What do you understand by time dilation? What is proper interval of time? Briefly discuss one experiment in support of time dilation in special theory of relativity. Derive and explain the law of radioactive disintegration. Also find the expression of decay constant in terms of mean life time. What is light? Discuss polarized light and optical rotation. Consider the reconstruction of the hologram as formed by a plane wave traveling along a direction parallel to the z-axis, Show it forms virtual and real image. (6× ×7 = 42)

Group (B) Short Questions: (Any six)

1. A particle of rest mass m0 moves with C/ 2 . Calculate its mass, momentum, total energy and kinetic energy. 2. Is mass of body changed in relativistic mechanics? Find the formula in order to explain it. 3. Calculate the permitted energy levels of an electron, in a box of 1A0 width. 4. Explain with neat diagram about G.M. counter. 5. Explain the principle of operation of linaces with neat diagram. 6. How Bragg's law is applied for the reconstruction of a thick hologram? 7. Discuss the applications of hologram. 8. What is quantum chromodynamics? Discuss electroweak interaction. (2× ×8 = 16)

Group (C) Very Short Questions: (Any eight) 1. Does mass of body change after heating? Explain. 2. State Einstein's theory of relativity. 3. “No thing in this universe is in rest position”. Explain. 4. State Wien's displacement law with example. 5. Explain about effect of radiation on living organisms. 6. State and explain de Broglie's hypothesis. 7. Modulation 8. Write on Modulation transfer function of human eye. 9. Hadrons 10. Synchronous detection 11. Quark model 12. Particles and antiparticles. ***