BEE Engineering Electromagnetics Fundamentals 5

Question 1

The magnetization M of a magnetic material is related to the magnetic susceptibility χ_m and H by:

Accepted Answer

M = χ_m H

Answer

By definition, M = χ_m H, where χ_m is dimensionless and positive for paramagnetic materials.

Question 2

In the method of images, a point charge +Q placed at height h above an infinite grounded conducting plane is equivalent to:

Accepted Answer

-Q at height -h (below the plane)

Answer

The image charge is -Q placed at distance h on the opposite side of the grounded plane to enforce V = 0 on the surface.

Question 3

Ampere's law with Maxwell's displacement current correction in integral form is:

Accepted Answer

∮H·dl = I_enc + ∬(∂D/∂t)·dS

Answer

Maxwell added the displacement current ∂D/∂t to Ampere's law: ∮H·dl = I_enc + ∬(∂D/∂t)·dS.

Question 4

The critical angle for total internal reflection when light passes from glass (n=1.5) to air (n=1.0) is approximately:

Accepted Answer

41.8°

Answer

θ_c = arcsin(1.0/1.5) = arcsin(0.667) ≈ 41.8°, the minimum angle for total internal reflection.

Question 5

The torque T experienced by a magnetic dipole m in a uniform magnetic field B is:

Accepted Answer

T = m × B

Answer

The torque is T = m × B, tending to align the magnetic moment with the applied field.

BEE - Bachelor of Electrical Engineering Practice Test