ELECTROMAGNETIC FIELD THEORY PAPER 3

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ELECTROMAGNETIC FIELD THEORY (B.Tech 4th Semester,2052)

NOTE:- This paper consist of Three Sections. Section A is compulsory. Do any Four questions from Section B and any two questions from Section C

Section-A Marks : 20

1(a) Write equation for superposition of electric field intensity from a wire, a surface, a volume.
(b) What is equation of continuity for steady currents ?
(c) Define Ampere's law.
(d) Write Maxwell's equation derived from Faraday's Law, in integral form.
(e) Which Maxwell's equation shows that normal component of Magnetic flux density B is continuous across
boundary of two mediums ?
(f) Write wave equation for electric field(along y-axis).
(g) Define characteristics impedence of free space.
(h) Which mode of wave propagation, occur in coaxial cable ?
(i) In TEmn, for what m and n subscripts stand for ?
(j) What are different types of Waveguides ?

Section-B Marks:5 Each

2. A square loop of wire, 20 cm by 20 cm, has a voltmeter connected in series with one side. Determine voltage
indicated by meter when the loop is placed in alternating magnetic field, the maximum intensity of which is 1 ampere
per meter. The plane of loop is perpendicular to magnetic field. Frequency is 10 mHz.
3. Derive an expression for inductance and capacitance per unit length of a coaxial transmission line.
4. Describe how TE10 and TE20 waves can be exited in reactangular waveguides.
5. Show how wave impedence for TE and TM wave between parallel planes vary as a function of frequency.
6. What is meant by uniform plane wave ? Derive wave equation in terms of electric field and magnetic field ?

Section-C Marks : 10 Each

7. (a) What is meant by polarization of an electromagnetic wave ?
(b) For reflection by a perfect insulator, with oblique incidence, derive an expression for reflected field strength
to indentical field strength ratio for vertical polarization ?
8. (a) Draw fdield configuration for TM, TE modes.
(b) Derive an expression for cut-off frequency for a rectangular waveguide.
(c) Show that for TM waves in rectangular waveguide the minimum attenuation arising from imperfect
conductors occur at f = 31/2fc.
9. Write notes on the following:
(a) Q factor of waveguide
(b) Reflection of waves by perfect insulators
(c) Boundary conditions.