PTU B.Tech Electrical Engineering 2nd Semester May 2019 71538 ELECTROMAGNETIC FIELDS Question Papers

PTU Punjab Technical University B-Tech May 2019 Question Papers 2nd Semester Electrical and Electronics Engineering (EEE)-EE-Electrical Engineering

Roll No.
Total No. of Pages : 02
Total No. of Questions : 09
B.Tech. (EE) (PT) (Sem.?2)
ELECTROMAGNETIC FIELDS
Subject Code : BTEE-403
M.Code : 71538
Time : 3 Hrs. Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
1.
SECTION-A is COMPULSORY consisting of TEN questions carrying T WO marks
each.
2.
SECTION - B & C. have FOUR questions each.
3.
Attempt any FIVE questions from SECTION B & C carrying EIGHT marks each.
4.
Select atleast T WO questions from SECT ION - B & C.

SECTION-A
1. Write briefly :

a. Given vectors A = 2ax + 4ay + 10az and A = 4ax + 8ay ? 5az, find the angle between A

and B.

b. If the magnetic flux density of a point in a region is 200 sin(120 t) a
2
z,mWb/m , What

is the curl of magnetic field intensity?

c. If the vector function F = (3y ?K1 z) ax + (K2 x ?2z) ay ? (K3y + z) az is irrotational, then

find the values of K1, K2 and K3 respectively.

d. State Gauss's Law.

e. State Stoke's theorem.

f. For a uniformly charged sphere of radius R and charge density , find the ratio of

magnitude of electric field at a distance R/2 and 2R from the centre.

g. Define magnetic flux density.

h. A uniform plane wave in air incident at 60? angle on a lossless dielectric material with

dielectric constant r. The transmitted wave propagates in a 30? direction with respect to

normal. Find the value of r.

i. An electric field is produced by point charges 1C and 4C located at (?2, 1, 5) and
(1, 3,?1), respectively. Find the energy stored in the field.

j. State Laplace equation and what is its significance?
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SECTION-B
2.
Derive the expression for magnetic field intensity due to infinitely long straight conductor
carrying a current I amps along Z-axis.
3.
In a nonmagnetic medium E = 4 sin(2 x l07t ?0.8z)ax V/m. Find the total power crossing
100 cm2 of plane 2z + y = 5
4 .
The electric field of an electromagnetic wave propagating in the z-direction is given by the
equation E = sin (t - z) ax + sin (t ? z + /2) ay Prove that the wave is left hand
circularly polarised.
5.
A medium is divided into regions about x = 0 plane as shown in fig. 1. An electromagnetic
wave with electric field E1 = 4ax + 3ay + 5az is incident normally on the interface from
region-1. Find the electric field E2 in the region-2 at the interface.
x<0
x>0
region 1(
r = 3,
1 =
0

= 0)
region 2(r = 3,
2 =
0

= 0)

Fig.1


SECTION-C
6.
Explain the concept of poynting vector and poynting theorem.
7.
Write down Maxwell's equations for time-varying fields in both differential and the
integral forms. Also write down the word statements of these equations from the
mathematical statements in the integral form and define their significance.
8.
What are the four basic rules for the boundary conditions at the interface of two different
materials? Derive an expression for the reflection coefficient of a uniform plane wave
Incident on a non lossy medium.
9.
The electric field of a plane wave is given by E = 20 cos(109t + 30z) ay V/m where ay is the
unit vector along the y-direction. Determine :

a. The magnetic field H

b. The phase velocity Vp

c. Dielectric constant r of the medium when = 0

NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.
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