# Mumbai University Previous year question papers

## V Sem Electronics Examination May 2008

## Electromagnetic Engineering

N. B.:

1) Question no. 1 is compulsory.

(2) Attempt any four questions from the remaining six questions.

(3) Assume any suitable data if necessary.

1. (a) State and explain Coulomb’s Law.

(b) Explain conduction current and displacement current.

~c) Explain the terms IIdistributed parameterll and IIlumped parameter II.

(d) Charge Q1 :;: 300 J.lc is located at (1, -1, -3) experiences a force

F1:;: Sax — Say + 4az N due to a point charge Q2 at (3, -3, -2). Determine Q2′

(e) Obtain ‘H’ due to infinitely long straight filament of current I.

2. (a) On a line described by x:;:~ 2, Y :;: -4 m, there is uniform charge distribution of 10

Pe :;: 20 nc/m. Determinethe electric field E at (-2, -1, 4).

(b) Charge lies in Z :;: -3 plane in the form of a square sheet defined by 10

\”2,.$.x2, -2 .$. Y .$. 2, with ~harge density Ps :;: 2 (x2 + y2 + 9)3/2 nc/m2. Find ,E at Origin.

3. (a) A uniform line charge of Pc 3 J.lc/mlies along z axis and concentric circular cylinder -1.5 of radius 2 m has PsJ.lc/m2.80th distributions are infinite in extent with Z. Use Gauss law to find 0 in all directions.

(b) GivenA:;: 30e-r ar – 2zazin cylindricalco-ordinatesevaluateboth sidesof divergence theorem by the volume enclosed by r:;: 2, z :;: 0 and

4.

(a) Find the work done in moving a point charge

~lC from origin to sphericalco-ordinatesystemin the field.

E5e-r/4 a + 10 a V/m rrsinS q>;””‘x

(b) Stateand explain8iot-Savert’sLaw.Derivethe expressionfor magneticflux densiD’

8 on the axis of circular ring of radius a at the distance ‘d’ from the plane of the ring.

5. (a) S~artingwith Maxwell’s equations derive the wave equation for a wave in conducting media and show that the wave gets attenuated when travelling in this medium.

(b) In the region 0 < r < 0.5, in cylindrical co-ordinates, the current density is given by 10),

J:;: 4.5 e -2r az A/m2. Or J :;: 0 elsewhere. Use Ampere law to find H. ‘s

6. (a) Given E :;: Em sin (wt – j3z)’ay in free space. Find 0, 8, H using Maxwell’s equation. 10.

(b) Derive the equation of standing wave. Find the instantaneous rate of energy flow per unit area ,at a point.

7. (a) Differentiate between scalar and vector magnetic potential.

(b) Maxwell’s equation in point as well as integral for steady electric and magnetic field.

(c) Derive Poisson’s.and Laplace equations.

(d) Impedance matching using Smith chart.

(e) State and explain Stoke’s theorm.