Deemed University 2011 B.Tech Electronics and Communications Engineering University: Lingayas University Term: V Title of the : Electromagnetic Theory - Question Paper

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Lingayas University

B.Tech. 2^nd Year (Term V)

Examination Feb 2011

Electromagnetic Theory (EC - 203)

 

[Time: 3 Hours] [Max. Marks: 100]

 

Before answering the question, candidate should ensure that they have been supplied the correct and complete question paper. No complaint in this regard, will be entertained after examination.

 

Note: Attempt five questions in all. All questions carry equal marks. Question no. 1 (Section A) is compulsory. Select two questions from Section B and two questions from Section C.

Section A

(Symbols are having their usual meanings)

Q-1. Part A

Select the correct answer of the following multiple choice questions. [10x1=10]

(i) The relationship between potential and electric field is

(a) (b)

(c) (d) None of these

(ii) The Gausss law for electrostatics can be mathematically represented as

(a) (b)

(c) (d)

(iii) For scalar field V and vector field, the div (VA) will be

(a) V div A (b) V div A + . div V

(c) V div A + A.grad V (d) Zero

(iv) The electrostatic energy due to n point charges is

(a) (b)

(c) (d)

(v) Divergence theorem can be expressed as

(a) (b)

(c) (d)

(vi) Divergence of can be expressed as

(a) div = - (b)

(c) (d)

(vii) Equation of continuity is

(a) (b)

(c) (d) None of these

(viii) Capacitance of an isolated conducting sphere (a < b) is

(a) (b)

(c) (d) None of these

(ix) Laplaces equation can be written as

(a) (b)

(c) (d) None of these

(x) The electric field is

(a) Normal (b) Tangential

(c) Opposite (d) Unrelated

to the electric equipotential lines.

 

Part B

 

(a) Describe gradient of a scalar field? Explain its physical significance.

(b) State Gausss divergence Theorem and Stokes Theorem. [2x5=10]

Section B

 

Q-2. (a) What is Gausss law? Explain. Find electric field intensity due to infinitely long line charge.

(b) Find expression for the capacitance of a spherical concentric shells of radii r₁ and r₂ with r₂ > r₁. [2x10=20]

 

Q-3. (a) Express Poissons and Laplaces equations in Cartesian coordinate systems.

(b) Explain Uniqueness Theorem. [2x10=20]

 

Q-4. (a) State and explain BiotSavarts Law. [10]

(b) Define:

(i) Intensity of magnetization. [5]

(ii) Magnetic induction. [5]

 

Section C

 

Q-5. (a) Derive differential form of Maxwells equations. [10]

(b) (i) Calculate the skin depth, at frequency of 1.6 MHz in aluminium where and [5]

(ii) A sinusoidal plane wave is transmitting through a medium whose breakdown voltage is 20 kV with h= 60 p. Find average power density. [5]

 

Q-6. (a) Explain the wave equation for and in conducting media. [10]

(b) The potential at a point P(-4, 3, 6) is given as V = 2x²y 5z, find the following values at P:-

(i) The potential

(ii) The electric field intensity

(iii) The direction of and

(iv) The electric flux density [10]

 

Q-7. (a) What is Poynting vector? Derive Poynting theorem and explain the physical meaning of each term.

(b) A sheet of charge is present at the plane x = 3 in free space and line charge is located at P (1, 0, 4). Find the magnitude of electric field intensity at the origin. [2x10=20]

 

Q-8. (a) A plane electromagnetic wave is incident normally at the interface of perfect dielectric. Derive reflection and transmission coefficient of. Define standing wave ratio (SWR).

(b) Transform the following vector to spherical coordinates. The vector is and P = (r = 4, q = 25⁰, f = 120⁰).

[2x10=20]