BSc Physics SEM V 2017 18 2017-18 Physics IV Question Paper - Mumbai University | munotes

Questions asked in this paper

• (2) Figures to the right indicate full marks

1. Q1 (a) Attempt any one:
   • (i) Find the potential inside and outside a uniformly charged solid sphere 10 whose radius is R and total charge is q, use infinity as your reference point Compute the gradient of V in each region and check that it yields the
   • (ii) A grounded conducting plane of infinite extent is kept coinciding with X-Y 10 plane, a point charge q is placed at a distance ‘d’ above the plane along Z axis using method of images obtain:
2. Q1 The position and the magnitude of image charge
3. Q2 Electrostatic potential at any point above the conducting plane and electrostatic field at any point on the conducting plane
   • (b) Attempt any one:
   • (i) Define Electric flux. State Gauss law in electrostatics. What are the merits 5 and demerits of Gauss law?
   • (ii) The electric field in some region is found to be E = k is a 5 constant, find the charge density p
4. Q2 (a) Attempt any one:
   • (1) Explain the term ‘Polarization’; obtain the expression for potential due to 10 polarized object in terms of bound charge densities
   • (ii) Starting from Biot-Savart’s law obtain the expression for Vx B ang V-B 10
   • (b) Attempt any
   • (i) Explain what is meant by linear homogeneous and isotropic dielectric, 5 Obtain the expression & vector field in vacuum is given check if it can 5 represent magnetic field, if yes then find the associated current density
5. Q3 (a) Attempt any one:
   • (i) the terms — Magnetic susceptibility and permeability. Describe in 10 brief the deceptive parallel between the equations =7 and ii)
   • (ii) Obtain the expression for energy stored in magnetic field. What is energy 10
   • (b) Attempt any one:
   • (i) Express J, and in terms of Show that =0 5
   • (ii) The magnetic susceptibility of a linear sample of Aluminum is ‘if 5 an auxiliary field of 2000 A-turns/m is applied along Z axis find the Magnetization and the Magnetic field in the medium
6. Q4 (a) Attempt any one:
   • (1) Starting from Maxwell’s equation obtain the wave equation. For plane 10 wave solution show that the electric field magnetic field and the direction of propagation are mutually perpendicular (li) Explain the term Poynting vector; hence obtain the expression for Poynting 10
   • (b) Attempt any one: Show that conservation of charge leads to the continuity equation. 5
   • (ii) In case of monochromatic plane waves show that the contributions from 5 electric field and magnetic field towards total energy density are same
7. Q5 (a) Attempt any one:
   • (i) the electric field due to potential V = x? +2y? +42? 4
   • (ii) An alpha particle with a kinetic energy of 1.7 x is shot directly 4 towards a platinum nucleus from a very large distance. What will be the distance of closest approach? The electric charge of the alpha particle is +2e and that of the platinum nucleus is +78e. Treat the alpha particle and the nucleus as spherical charge distributions and disregard the motion of
   • (b) Attempt any one:
   • (i) that for linear isotropic homogeneous dielectrics, volume bound 4 charge (pp) is proportional to volume charge density of free
   • (ii) A very long closely wound solenoid has 3000 turns per metre; it carries a 4 current of 2 amperes, Find the magnetic field inside the solenoid
   • (c) Attempt any one:
   • (i) infinite solenoid with ‘n’ turns per unit length carrying a current ‘I’ and 4 filled with linear material of susceptibility find the Magnetic field B inside the solenoid
   • (ii) A long copper rod of radius ‘R’ carries a uniformly distributed free current 4 find H inside and outside the rod,
   • (d) Attempt any one:
   • (i) Dielectric constant of diamond is 5.5, if the permeability of diamond 3 ) is same as the permeability of free space = Find the refractive index of diamond
   • (ii) IfR is the reflection coefficient and T is the transmission coefficient then 3

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