# Mumbai University Previous year question papers

Table of Contents

## V Sem Electronics Examination May 2009

## Electromagnetic Engineering

1.

(a) Write down Maxwell’s equation~sin phasor form and derive the wave equation for Electric field.

(b) Exp.lainthe significance of the propagation constant and arrive at expressions for its real and imaginary parts for a uniform plane wave.

(c) Derive Ampere’s circuital law in point form for circuits that include capacitors. 10

2. (a) Derive loundary conditions for field vectors E, 0,8 and H. 10

(b) State Poynting theorem and derive the expression for instantaneous Poynting vector.

3.

(a) Derive expressions for the reflection and transmission coefficients of a perfect dielectric when a plane e.m. wave is incident normally on it.

(b) For free space, show that the intrinsic impedance is equal to 377 ohms. 10

4.

(a) Obtain the transmission line equations for a two wire transmission line. Define 10

characteristic impedance of the transmission line. Derive an expression for its characteristic impedance.

(b) A load of impedance ZL = 50-j 1000 is connected to a lossless transmission line of characteristic impedance Zo=1000. The line operates at 300 MHz and the speed of propagation on the line is O.BC.Calculate-

(i) the input admittance at a distance of 2.5 m from the load.

(ii) the input impedance at a distance of 2.5 m from the load.

Use Smith chart.

5. (a) For an e.m. wave travelling between a pair of parallel perfectly conducting infinite planes, analyse the TE mode. .

(b) An electromagnetic wave propagates downward from an aircraft and into water at frequency of 10 GHz. Assume water has no loss and a relative permittivity of 81Neglecting interface effects, Calculate-

(i) the wave no. in air

(ii) the wave no. in water.

6. Show that the power radiated by a dipole is P = BOn2 12(d.I)2rms

7. Write short notes on :-

(a) Displacement Current

(b) Gauss’s Law

(c) Poisson’s equation

(d) Impedance Matching.