Electronics And Telecomm (Semester 5)
Total marks: 70
Total time:150 mins
INSTRUCTIONS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Draw neat diagrams wherever necessary.
1.a.
State and prove Gauss Theorem.
(5 marks)
00
1.b.
A 5nc point charge is located at A (2,-1,,3) in free space. Find Electric Field Intensity at origin .
(5 marks)
00
OR
2.a.
State the relation between Electrostatic potential & Electric field intensity .
(5 marks)
00
2.b.
If D = 5x / 2 ax $\mathrm{c} / \mathrm{m}$ Evaluate both sides of divergence theorem for volume of cube 1 m to an edge centered at origin & edges parallel to the axis.
(5 marks)
00
3.a.
Derive the boundary condition at an interface between conductor and
free space.
(6 marks)
00
State and prove Biot Savarts law.
(4 marks)
00
OR
4.a.
An infinite long straight filament carrying current 3 A is placed along z-
axis. Calculate magnetic field intensity at p(l,2,1)
(5 marks)
00
4.b.
State and explain stockes theorem.
(5 marks)
00
5.a.
Write Maxwell's equations in point & integral form for time varying field & free space.
(8 marks)
00
5.b.
Define conduction current & conduction current density? Derive current continuity equation.
(10 marks)
00
OR
6.a.
State and prove Poynting theorem.
(8 marks)
00
6.b.
The Electric field intensity $\overline{\mathrm{E}}$ = 250 $\sin 10 \mathrm{t} \mathrm{v} / \mathrm{m}$ for afield propagating in a medium whose $\sigma=5.0 \mathrm{s} / \mathrm{m} \& \in_{r}=1.0$ Calculate Jd, Jc and frequency at
which Jc = Jd.
(10 marks)
00
7.a.
Explain various primary and secondary parameters of Transmission line.
(6 marks)
00
7.b.
A transmission in has following primary constants:
R = 11 $\mathrm{ohm} / \mathrm{Km}$, G = 0.8 $\mathrm{ohm} / \mathrm{Km}$, L = 0.00367 $\mathrm{H} / \mathrm{Km}$, C = 8.35 $\mathrm{nf} / \mathrm{Km}$.At a single of 1 KHz.
Calculate:
i) Characteristic impedance
ii) Attenuation constant
iii) Phase constant
iv) wavelength
v) Velocity.
(10 marks)
00
OR
8.a.
What is distortion less, line? I Derive the expression for characteristic impendence and propagation constant for distortion less line.
(6 marks)
00
8.b.
A lossless 100 ohm transmission line is terminated in an impedance 50 + j60 ohm.
Calculate
i) VSWR
ii) Reflection coefficient.
iii) Impedance of 0.35 ohm from load using smith chart.
(10 marks)
00
9.a.
Derive from Maxwell's equations the wave equation in vector form for Electric Field Intensity in free space.
(8 marks)
00
9.b.
Find skin depth at frequency of 1.6 MHz in aluminum whose $\sigma=38.2 \times 10^{-3} \mathrm{s} / \mathrm{m} \& \mathrm{k}$ new $\mu=1.0$ Also find propagation constant and wave velocity propagating in that medium $(\alpha=\beta=1 / \delta)$
(8 marks)
00
10.a.
Define dept of penetration. Derive expression for depth of penetration for a good conductor.
(8 marks)
00
10.b
A 10GHz plane wave travelling in free space as an amplitude Ex = 10 $\mathrm{V} / \mathrm{m}$.Find $\mathrm{V}, \lambda, \beta, \eta$ and amplitude & direction of H.
(8 marks)
00
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