# Electromagnetic Theory 4th Sem June 2003

(Electrical /Electronics and Telecommunication. Engineering)

Note: Attempt one question from each unit. All question carry equal marks.

1   (a) Show that the expression for the potential due to an electric dipole satisfies the Laplace equation.

(b) Starting from Gauss‘s law drive passion’s and Laplace’s equation.

2    (a) Drive the execration for the energy stored in a magnetic filed.

(b)  Calculate the magnetic flux density produce by a current lop of radius ‘R’ on the axis when the loop is carrying a current ‘I ’situated in air .

3   (a) Proved that the curl of gradient of a scalar is zero.

(b) Calculate the magnetic flux distantly produced by infinite thin wire carrying current I at a distance.

4   (a) Drive the boundary condition for electric and magnetic fields.

(b) Define pointing vector and given its physical interpretation forms.

5   (a) Explain Maxwell’s equation in integral and differential forms.

(b) Explain Ampere’s circuital law.

6   (a) what do you understand by redaction pattern? Obtain the radiation pattern for centre fed vertical

dipole of one half wavelengths.

(b) Find the redaction resistance of an infinitesimal dipole whose overall length is λ/50. Drive the relation for the same.

7  (a) Explain the following :

(i) Radiation field       (ii) retarded vector potential     (iii) induction field

8.  Write short notes on any three of the following:

(i) Skin depth   (ii) Coulomb’s law    (iii) Displacement current      (iv) Magnetic flux density