Andhra University 2007 B.E ELECTRO MAGNETIC FIELD THEORY - Question Paper

II Year B.E./B.Tech Degree exams

ELECTRO MAGNETIC FIELD THEORY

Electronics & Communication Engineering

Time : 3 hours Maximum : 75 Marks

ques. one is compulsory

ans any 4 from ques. two to 8

All ques. carry equal marks



to 0.04 m2. The plates are separated by a dielectric material

whose r two Î = with the plate separation of 1cm. obtain (a) its

capacitance value (b) the charge on the plates when a

potential difference of 10 V is applied (c) the energy stored.

5. a) Derive the expressions for Maxwell’s equations in time

varying fields and discuss their meaning.

b) In free space, the magnetic field of an EM wave is provided by

H=0.4wÎocos(wt-50x)azA/m. obtain the electric field,

E and displacement current density, D.

6. a) What is an Ampere’s circuit legal regulations and derive an expression

for differential form of ampere’s circuit legal regulations.

b) The radii of the inner and outer conductors of a coaxial cable

are two mm and six mm respectively and m=m0 . obtain the

inductance of a 10m long cable.

7. a) provide a general solution of uniform place wave formula and

also derive an expression of relation ranging from E and H in

uniform plane wave.

b) The wavelength of an x-directed plane wave in a lossless

medium is 0.25m and the velocity of propagation is

1.5 ´ 1010 cm / sec . The wave has z-directed electric field

with an amplitude equal to 10 V/m. obtain the frequency and

permittivity of the medium. The medium has m=m0.

8. a) Derive an expression of guide wavelength in circular

waveguides.

b) A transmission line is lossless and is 25 m long. It is terminated

in a load of ZL=40+j30W at a frequency of 10 MHz.

The inductance and capacitance of the like are

L=300nH/m, C=40 pF/m. obtain out input impedance at

the source and at midpoint of the line.

Earning:   Approval pending.