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FOURTH SEMESTER (CUCBCSS—UG) DEGREE EXAMINATION
APRIL 2020
Physics/Applied Physics
PHY 4B 04/APY 4B 04—ELECTRODYNAMICS—I

Maximum : 80 Marks

Time : Three Hours

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&छ 9 AND

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12.

13.

14.

Section A

Answer al] questions.
Each question carries 1 mark.
Answer in a word or phrase.

State Gauss’s law in differential form. Explain the symbols used.

Give the relation between vector potential and magnetic field.

If the electrostatic potential in a region is represented as V = ‏ہو‎ + 3y —z, obtain the expression for
electric field strength.

Write down the wave equation in one dimension.

What are equipotential surfaces ?

State whether the statement is True or False :

If the electric field is zero at a point, the electric potential is necessarily zero at that point.

The number of electric field lines penetrating normal to a surface is called electric flux.

Above the Curie temperature, a ferromagnetic material would become paramagnetic.

CO, is an example of non polar molecule.
In the interior of a dielectric kept in a uniform field, the net charge is zero.
(10 x 1 = 10 marks)

Section B

Answer all questions in two or three sentences.
Each question carries 2 marks.

Show that electrostatic energy does not obey superposition principle.

Define one ampere current using the expression for the force acting per unit length of long parallel

current carrying conductors.
Find the vector potential of an infinite solenoid with n turns per unit length, radius R and
current I.
Is dielectric an insulator ? Explain.
Turn over