B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2010
Fourth Semester
Electronics and Communication Engineering
EC2253 — ELECTROMAGNETIC FIELDS
(Regulation 2008)
Time: Three hours Maximum: 100 Marks
Answer ALL Questions
PART A — (10 ﾗ 2 = 20 Marks)
1. State Stoke’s theorem.
2. Define electric scalar potential.
3. State Biot-Savart law.
4. Write down Lorentz force equation.
5. Define dielectric strength of material and give its unit.
6. What do you mean by Magnetization?
7. What is Displacement current density?
8. State Poynting vector.
9. What is skin effect?
10. Define Brewster angle.
PART B — (5 ﾗ 16 = 80
Marks)
11. (a) (i) Given the two points
A(x = 2, y = 3, z = −1) and ( _ _ ) B r = 4, è = 25 , ö = 120 .
Find the spherical co-ordinates of A and Cartesian
Co-ordinates of
B . (8)
(ii) Find curl
H , if ( ) z H
= 2 cos a
− 4 sin a
+ 3a
ñ ö ñ ö ñ ö . (8)
Or
(b) (i) A circular disc of radius ‘a’ m is
charged uniformly with a charge of
ó c/m2. Find
the electric field intensity at a point ‘h’ metre from the
disc along its axis. (8)
(ii) If
+
= + − 2
2
2
4
2 20
x y
V x y z volts, find E
and D
at P(6,− 2.5, 3).
12. (a) (i) State and explain Ampere’s circuital law. (8)
(ii) Find an expression for H at any
point due to a long, straight
conductor carrying I amperes. (8)
Or
(b) (i) Find the maximum torque on an 85 turns, rectangular
coil with
dimension (0.2 ﾗ 0.3)m, carrying a current
of 5 Amps in a field
B = 6.5T . (8)
(ii) Derive an expression for Magnetic vector potential. (8)
13. (a) (i) Derive Poisson’s and Laplace’s equation. (8)
(ii) A parallel plate capacitor has an area of 0.8 m2, separation of
0.1 mm with a dielectric for which = 1000 r
å and a field of 6
10 V/m.
Calculate C
and V
. (8)
Or
(b) (i) Derive an expression for the inductance of solenoid.
(8)
(ii) Derive the boundary conditions at an interface between
two
magnetic Medias. (8)
14. (a) (i) Derive modified form of Ampere’s circuital law
in Integral and
differential forms. (8)
(ii) Find the amplitude of displacement current density
inside a
capacitor where = 600 r å and
6
3 10D
= ﾗ − ( 6 ) 2
sin 6 10 0.3464 c/m z
ﾗ t − x a . (8)
Or
(b) (i) Derive Maxwell’s equation derived from Faraday’s law
both in
Integral and point forms. (8)
(ii) In free space, ( ) z H
= 0.2cos wt − âx a A/m. Find
the total power
passing through a circular disc of radius 5 cm. (8)
15. (a) (i) Derive the general wave equation. (8)
(ii) Discuss the wave motion in good conductors. (8)
Or
(b) Explain the reflection of plane waves by a perfect
dielectric. (16)
—————————
.jpg)
0 comments:
Post a Comment