MSc Physics (Electronics I) SEM II 2018 19 May 2018-19 PHYSICS PAPER II ELECTRODYNAMICS Question Paper - Mumbai University | munotes

Questions asked in this paper

• (2) Figures to the right indicate full marks

1. Q1 (a) Attempt any one:--- 8 marks
   • (i) What is Poynting vector S? Obtain the expression for Poynting theorem Explain which physical quantity is expressed by S/c?
   • (ii) Write the x, y and z components of the following equations Ahence define field tensor and express it as a matrix
   • (b) Attempt any one:--- 04
   • (i) Express the law of conservation of linear momentum in electrodynamics in terms of
   • (ii) Explain why the tail of a comet is always directed away from the Sun
2. Q2 (a) Attempt any one:--- 8 marks
   • (i) Using Maxwell’s equations in vacuum obtain the wave equations for B and E. Write down the solutions of these equations and show that for electromagnetic waves travelling in vacuum, the amplitudes of the electric and magnetic vectors are the Gi) Obtain = for frequency dependence of the conductivity. Discuss two cases for frequency dependence of the conductivity
   • (b) Attempt any one:--- 04 electric field corresponding to certain plane monochromatic wave is Then comment on the state of polarization
   • (ii). Write expressions for the real and imaginary parts of atomic polarizability and explain normal and anomalous dispersion with the help of neat diagram
   • Q.P. Code: 50588
3. Q3 (a) Attempt any one:--- 8 marks
   • (i) Obtain an expression for the electric field and magnetic field produced by a charged particle in uniform motion, hence draw and explain polar plot of electric Show that a total power radiated from a non-relativistic accelerated. charge is
   • (ii) given by
   • (b) Attempt any one:--- 04
   • (i) Show that the retarded potentials leads to the generalized Coulomb-Faraday law where R = lr r| and vector along R
   • (ii) Write down Maxwell-Ampere’s equation in terms of scalar potential t) and vector potential substitute Lorentz’ gauge condition in it and obtain the
4. Q4 (a) Attempt any one:--- 8 marks
   • (i) Construct energy momentum tensor Tyy and get the energy conservation law from
   • (ii) Write the Lagrangian for relativistic charge particle in electromagnetic field and obtain the equation of motion Attempt any one:--- 04 Write the components of four vector current density hence write the continuity equation in four vector notation
   • (ii) Express Lorentz gauge condition in four vector notations
   • Q.P. Code: 50588
5. Q5 Attempt any four:--- 12 marks
   • (i) The radiant power of the Sun is watts. Find the radiation pressure on a completely absorbing area near the Earth.(The distance between the Earth and
   • (ii) Write the Maxwell equations in differential form (ili) Replacing vector operator V by ik and by —iw , write modified Maxwell equations in matter
   • (iv) What is penetration depth? Calculate penetration depth for light frequency
   • (v) State the advantages of writing Maxwell equations in terms of scalar potential and vector potential A
   • (vi) In the case of charged particle with collinear velocity and acceleration, draw polar plot and explain it
   • (vii) Explain the physical meaning of the equation E? —B? =E
   • (viii) Write down the components of

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