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College : Vardhaman College Of Engineering
Degree : B.Tech
Department : Electronics & Communication Engineering
Semester : IV
Subject : Electromagnetic Theory & Transmission Lines
Document type : Question Paper
Website : vardhaman.org

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Vardhaman Electromagnetic Theory Question Paper

VARDHAMAN COLLEGE OF ENGINEERING
Four Year B. Tech IV Semester Regular/Supplementary Examinations May – 2014
(Electronics and Communication Engineering)
All parts of the question must be answered in one place only

Related : Vardhaman College Of Engineering Computer Architecture & Organization B.Tech Question Paper : www.pdfquestion.in/6331.html

Unit – I

1. a) Point charges 1mc and -2mc are located at (3, 2, -1) and (-1,-1,4) respectively. Calculate the electric force on a 10nc charge located at (0, 3, 1) and the electric field intensity at that Point. 8M
b) If 2/3 1 2cos sin / r J a a A m r Calculate the current Passing through
i. A Hemi Sphere shell of radius 20 cm, 0 ;0 2 2
ii. A spherical shell of radius 10cm 7M

2. a) Determine the electric field intensity due to infinite sheet of charge using Gauss’s Law. 6M
b) Conducting Spherical shells with radii a=10cm and b=30cm are maintained at potential difference of 100V such that V(r=b)=0 and V(r=a)=100v. Determine V and E in theregion between the shells if 2.5 9M

Unit – II

3. a) Determine the magnetic field intensity at point P due to straight filamentary conductor of finite length. 6M
b) Given the magnetic vector Potential 2 z A a Wb/m, calculate the total magnetic flux crossing the surface ,1 2 ,0 5 2 m z m ? 9M
4. a) A circular loop located on x2 ? y2 ? 9; z ? 0 carries a direct current of 10A along a? . Determine H ? at (0,0,4) and (0,0,-4). 8M
b) In cylindrical Coordinates a magnetic field is given as H ? = 4 2 2 a? ?? ? ? ? ?? (A/m), 0 = ? = 1.
i. Find the current density as a function of ? within the cylinder
ii. Find the total current that passes through the surface z=0 and 0= ?= 1(m) in the aZ direction

Unit – III

5. a) State Maxwell’s equation in differential and integral form for time varying field. 6M
b) The electric and magnetic field in frees space are given by A/M Express these in phasor form and determine the constants 0 H and B such that the fields satisfy Maxwell’s equation. 7M
6. a) What is the significance of boundary conditions? Also derive an expression for the law of refraction for magnetic flux lines at a boundary with no surface current. 7M
b) Given that 1 2 6 4 / x y z H ? ? a ? a ? a A m in region y ? x ? 2 ? 0 where 1 0 ? ? 5? calculate 1 B , 2 H and 2 B in region y ? x ? 2 ? 0 where 2 0

Unit – IV

7. a) State and prove Poynting’s theorem. 9M
b) A uniform plane wave propagating in a perfect dielectric medium has (v/m) and (A/m). If the wave is travelling with velocity u = 0.5c. Find and intrinsic impedance of medium6M
8. a) Derive the expression for reflection coefficient when an electromagnetic wave is incident normally on to the surface of a perfect dielectric in terms of 1 and 2 7M
b) Given a uniform plane wave in air as 40cos ? ? 30sin ? ? / i x y E ? ?t ?? z a ? ?t ?? z a V m find i H
i. If the wave encounters a perfectly conducting plate normal to the z axis at z=0, find the reflected wave r E and r H .
ii. What are the total E and H fields for z ? 0 ?
iii. Calculate the time – average Poynting vectors for z ? 0 and z ? 0 8M

Unit – V

9. a) Derive the general solution for voltage and current at any point on a transmission line in terms of sending end voltage and sending end currents.9M
b) A certain transmission line 2m long operating at ? ? 106 rad/s has ? ? 8 dB/m, ? ?1 rad/m, and 0 Z ? 60 ? j40?. If the line is connected to a source of 10 00V , 40 t Z ? ? and terminated by a load of 20 ? j50? , determine:
i. The input impedance
ii. The sending – end current
iii. The current at the middle of the line 6M
10. a) What is the condition for transmission line to be lossless? Derive the expression for attenuation constant, phase constant and characteristic impedance for a lossless transmission line. 6M
b) A distortionless line has 0 z ? 60?, ? ? 20mNp / m u ? 0.6c . Where ‘c’ is the speed of the light in vacuum. Find R, L, C, G and ? at 100MHz. 9M