Bharathiar University 2001 M.Sc Physics Electromagnetic Theory and Electrodynamics - Question Paper
Degree
I
Reg. Mo, ---------------------------
(For the candidates admitted from 1999 onwards) M.Sc, DEGREE EXAMINATION, NOVEMBER 2001, Second Semester m
ELECTROMAGNETIC THEORY AND ELECTRODYNAMICS
Time s Three hoars Maximum; 100 marks
Answer ALL questions,
SECTION A (10 x 2 * 20 marks)
Answer-AJJ.-iuesticms in 1 or 2 sentences,
1. State Thomsons theorem,
2. What is meant by displacement current density?
3. Mention the equation for cut-off wavelength,
4. What is meant by coherent Battering?
5. . What is meant by four-vectors? '
Choose the correct answer:
6. The insulators wliose behaviour gets modified ia the electric field is ,,
(a) conductor (b) semi conductor
(c) dielectrics (d) none.
7. The medium which does not contain generators of . voltage and currents is -medium.
(a) Source free (fa) Homogeneous
(c) Isotropic (d) None.
8. Formulae relating amplitude of reflected and transmitted waves with that of incident wave are known as formulae.
(a) Fresael (b) Laraor
(c) Thomson (d) Brewster.
9. "When the' phas= difference between any two waves varies in a completely random way, they, axe said to be '' '
*
(a) coherent (b) incoherent
(c)' scattered (d) in phase.
10. Antisymmetric tensor is also known as tensor.
(a) Electromagnetic field Cb) Homogeneous
SECTION B (5 x 4 = 20 marks)
Answer ALL questions, choosing either (a) or (b),
XI. (a) Prove that er = !+&.
Or
%
(b) ffifferentiate between polar and n&a-polar molecules.
12. (a) Mention the differential form of Maxwell's equations.
'. " Or
:, (b) : A broadside antenna consists of 10 aerials hating A/2 mmoa separation. Find out the width of mala lobe.
13. (a) Prove that for a glass interface (m = 1.5 and m = 1.0} for normal incidence the reflection and transmission coefficients are 0.04 and 0.96 respectively.
Or
(b) What is meant by Total internal reflection?
14. (a) What is meant by resonant scattering?
Or
(b) Why red light is used for danger signals?
15. (a) What are the postulates of theory of relativity?
Or
b> Define Lora:.:? force law.
SECTION C (5 x 8 = 40 marks)
Answer ALL questionsroosing either (a) or (b).
16. (a; Derive Clatsris - Mossotti relation.
Or
<> ' Show that the cavity definition for the electric field inside dielectric depends on the shape of the cavity.
17. (a) Derive the equation of continuity.
(b) Deduce poynting theorem from Maxwells relations,
18, (a) Explain the reflection and refraction at the boundary of two non-conducting mdia.
Or
(b) What must fee the width of a rectangular guide such that' the energy of electromagnetic radiations whose free space wavelesgth is 3 cm, travels
down the guide at 98% of the speed of light.
19. (a) Derive expression for Thomson scattering of a free electron.
(b) Derive expression for Rayleigh's scattering cross section for a honnd electron,
_
20, (a) Find the component of wave four -vector, show that its square is zero.
(b) Show that the self product of electromagnetic field Tensor is given by Ft =2 J? -
5 3046
SECTION D (2 x 10 = 20 marks)
Answer ALL questions, choosing either (a) or fb),
21, (a) Derive esspreasiotl for volume forces in the electrostatic field,
Or
(b) Calculate the value of poynting vector at the surface of the sun if "the power radiated by the sun is 3,8 x 10* waH? and its radius is 7 x IP Km. Find the solar eier incident on the earth, if the average distance between the sun and earth is 1.5 x 10n meters.
22. (a) Derive expression for energy flow due to a plane electromagnetic wave in free space.
Or
(b) Explain the phenomenon of Normal and enonalous dispersion.
!
|
Attachment: |
| Earning: Approval pending. |
