(SEM V) THEORY EXAMINATION 2017-18 FUNDAMENTALS OF ELECTROMAGNETIC THEORY

Fundamentals of Electromagnetic Theory (NEC-508)

Section-Wise Important Questions & Study Notes

SECTION–A

(Attempt all questions | 2 × 10 = 20)

This section checks basic concepts, definitions, and formulas.
Write short, crisp answers (2–3 lines).

1. Unit Vector Parallel to a Given Vector

To find a unit vector parallel to a vector A, divide the vector by its magnitude.
Unit vector = A / |A|

2. Faraday’s Law

Faraday’s law states that an EMF is induced in a circuit whenever the magnetic flux linking the circuit changes with time.

3. Electric Dipole Moment

Electric dipole moment is the product of charge magnitude and the distance between two opposite charges, directed from negative to positive charge.

4. Dielectrics and Their Types

Dielectrics are insulating materials that store electrical energy.
Types include polar and non-polar dielectrics.

5. Coulomb’s Inverse Square Law

The force between two point charges is directly proportional to the product of charges and inversely proportional to the square of the distance between them.
The force acts along the line joining the charges.

6. Types of Magnets & Magnetic Flux Lines

Types: permanent, temporary, and electromagnets.
Magnetic flux lines form closed loops, never intersect, and show direction from north to south.

7. Loss Tangent & Loss Angle

Loss tangent is the ratio of dielectric loss to stored energy.
Loss angle is the angle between current and voltage in a dielectric.

8. Displacement Current

Displacement current is the current produced due to time-varying electric fields, even in the absence of charge flow.

9. Energy Stored in Magnetic Field

Energy stored in a magnetic field is given by
W = ½ LI² or expressed in terms of magnetic field intensity.

10. Transformer EMF Equation                 EMF equation of transformer:           E = 4.44 f N Φm

 SECTION–B

(Attempt any THREE | 10 × 3 = 30)
 Conceptual + derivation-based questions.

1. Area Using Spherical Coordinates

You must know:                                                    Spherical coordinate system

Differential area element                                      Limits of integration
Write steps clearly and refer to diagram.

2. Electrostatic Boundary Conditions

Explain boundary conditions at conductor–free space interface:        Tangential electric field

Normal electric flux density                                                                     Continuity conditions
Include derivation and neat diagram.

3. Biot–Savart Law & Force Between Conductors

State Biot–Savart law and derive expression for magnetic field.
Then derive force per unit length between two parallel current-carrying conductors.

4. Uniform Plane Wave Problem

Numerical based on:                                                   Attenuation constant (α)

Phase constant (β)                                                      Magnetic field intensity (H)
 Write formulas first, then substitute values.

5. Maxwell’s Equations                                               Write all four Maxwell’s equations:

Integral form                                                              Differential form
Also explain physical meaning briefly.

SECTION–C

(Attempt any TWO | 5 × 2 = 10)
Mathematical and theorem-based questions.

1. Stokes’ Theorem

State the theorem, explain its meaning, and prove it using vector calculus.

2. Gradient, Divergence & Curl

Explain:                                                  Physical meaning

Mathematical expressions                    Use in different coordinate systems (Cartesian, cylindrical, spherical)

3. Divergence Theorem

State and prove divergence theorem.    Explain its importance in electromagnetic theory.