ELECTROMAGNETIC FIELDS JNTU previous years question papers

ELECTROMAGNETIC FIELDS JNTU previous years question papers

Time: 3 hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks

1. (a) E is the electric field due to a point charge Q C at the origin in free space.Find s
SE.da where S is a spherical surface of radius R m and center at origin.
(b) Using Gauss’s law, show that the electric field due to an infinite straight line of uniform charge density ? C/m along the z-axis in free space is (?/2pe0r) ar N/C.
(c) An infinitely long cylinder of radius 1m in free space is filled with a uniform charge density of 1nC/m3. If the potential on the axis of the cylinder is 100 V, find the potential variation inside the cylinder. [6+6+4]

2. (a) For a conducting body in the electric field of static charges, explain what will be the
i. net electric field inside the conductor, and
ii. potential difference between different points inside the conductor.
(b) Two thin concentric spherical conducting shells of radii 2 cm and 3.5 cm are located in free space with their center at origin. If the potentials of the inner and outer shells are -25 V and 150 V respectively, find the surface charge densities on the shells. [8+8]

3. (a) Define polarization. Explain how a dielectric acquires polarization.
(b) A long straight line of uniform charge density ? C/m is surrounded by an insulating medium out to a radius R m. Find D. Also find the electric field in the region outside the insulation. Explain why the electric field cannot be found in the insulation region. [8+8]

4. A steady current configuration in free space is as shown in figure 4.
Find the magnetic field B at the point P, starting from Biot-Savart’s law.

5. (a) Determine H for a solid cylinder conductor of radius ?, where the current I is uniformly distributed over the cross section.
(b) Two infinitely long and parallel wires carry currents I1 - I2 = I Amps in opposite direction. They are separated by a distance of 17.32 cm. If the magnetic field intensity at a point, 10 cm from one wire and 20 cm from other is 13.783 A/m, determine the value of I. [8+8]

6. (a) Prove that the force on a closed filamentary circuit in a uniform magnetic field is zero
(b) If the magnetic field is H = (0.01/µ0) ax A/m, what is a force on a charge of 1 pC moving with a velocity of 106 ay m/s . [8+8]

7. (a) Obtain the expression for coefficient of coupling between two coils.
(b) A coil of 10 mH is magnetically coupled to another coil of 600 µH. The coefficient of coupling between two coils is 0.15. Calculate the inductance if these two coils are connected in parallel addition and parallel opposition. [8+8]

8. (a) In free space E=Em sin (?t - ßz) ax V/m, from Maxwell’s equation, find H.
(b) The circular loop conductor having a radius of 0.15 m is placed in X-Y plane. This loop consists of a resistance of 25 Ohms. If the magnitude of flux density is B = 0.5 sin 103 t az Tesla, find the current flowing through the loop

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