Download PTU (Punjab Technical University) B.Tech (Bachelor of Technology) / BE (Bachelor of Engineering) 2021 January EE 3rd Sem 76384 Electromagnetic Fields Previous Question Paper
Total No. of Pages : 02
Total No. of Questions : 18
B.Tech.(EE) (2018 Batch) (Sem.?3)
ELECTROMAGNETIC FIELDS
Subject Code : BTEE-304-18
M.Code : 76384
Time : 3 Hrs. Max. Marks : 60
INST RUCT IONS T O CANDIDAT ES :
1 .
SECT ION-A is COMPULSORY cons is ting of TEN questions carrying TWO marks
each.
2 .
SECT ION-B c ontains F IVE questions c arrying FIVE marks eac h and s tud ents
have to atte mpt any FOUR q ues tions.
3 .
SECT ION-C contains THREE questions carrying T EN marks e ach and s tudents
have to atte mpt any T WO questio ns.
SECTION-A
Write briefly :
1.
Obtain the expression for Laplacian of a scalar field for cylindrical coordinate system.
2.
State the significance of displacement current in the context of Maxwell's equations.
3.
If a lightning stroke with current 50 kA occurs 100 m away from your house, calculate
the magnetic flux density at your house due to the lightning stroke.
4.
Show that in a good conductor, skin depth is always much shorter than its wavelength.
5.
Find ( A B )
6.
Infinite line x = 3, z = 4 carries 16 nC/m and is located in free space above the conducting
plane z = 0. Use method of images to obtain the induced surface charge density on the
conducting plane at (5, ?6, 0).
7.
State Gauss's law.
8.
Express Coulomb's law in vector form.
9.
Find the equivalent inductance of two coils connected in series. Assume the fluxes to be
opposing each other.
10. Distinguish between transformer and motional emf.
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SECTION-B
11. If r x ax y a y z az is the position vector of (x, y, z), r = | r | and `n' is an integer,
evaluate-
a) ( n
r
r )
b)
2
(ln r )
12. Find D at P (6, 8, ?10) because of ?
(i) Point charge of 50 mC at origin
(ii) A uniform line charge L = 30 C/m on z-axis.
(iii) A uniform surface charge density s = 27.2 C/m2 on a plane x = 12.
13. Prove that :
A .C
B .C
( A B ). ( C D )
A.D B .D
14. Derive Biot Savart's law and Ampere's Circuital law from the concept of magnetic
vector potential.
15. Obtain the intrinsic impedance for an EM wave propagating through perfect conductor.
SECTION-C
16. State Divergence theorem and verify the same for the vector field
2
A r a
r sin
r
cos a over the surface of a quarter of a hemisphere defined by 0 < r < 3, 0 <
<
, 0
.
2
2
17
If A 2a
4
x
a y and B 6a ? 4
y
az . Find the smaller angle between them using cross
product. Verify it using dot product. Apply triangle law of vector addition to establish
Coulomb's law of force between two-point charges.
18. If F 2 z
a 3 z sin a 4cos a
z verify Stoke's theorem for the open surface
defined by z = 1, 0 < < 2, 0 < < 45?. What is a time harmonic field? Derive Ampere's
circuital law for time harmonic fields.
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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This post was last modified on 26 June 2021