Electromagnetic Fields and Waves MCQs (Part-7)

What is the electric field produced by a point charge proportional to?

A \( Q \times r^2 \)
B \( Q \times r \)
C \( Q / r^2 \)
D \( Q / r \)

What is the principle behind Gauss’s Law in electromagnetics?

A The electric field due to a charge distribution is proportional to the charge
B The magnetic flux through a surface is proportional to the current passing through the surface
C The electric flux through a closed surface is proportional to the total enclosed charge
D The electric field is inversely proportional to the square of the distance from a charge

Which law describes how a time-varying magnetic field generates an electric field?

A Ampere’s Law
B Gauss’s Law
C Faraday’s Law
D Biot-Savart Law

What is the role of displacement current in Ampere’s Law?

A It accounts for the contribution of magnetic fields from moving charges
B It accounts for the changing electric field in regions where no current is present
C It increases the electric flux through a surface
D It changes the direction of current flow

What is the basic principle of an antenna in communication systems?

A To amplify electromagnetic waves
B To convert electrical signals into electromagnetic waves and vice versa
C To reflect waves in different directions
D To store energy in electromagnetic fields

What does the term “polarization” refer to in the context of electromagnetic waves?

A The speed of wave propagation in a material
B The direction of the electric field vector of the wave
C The interference pattern formed by the wave
D The intensity of the electromagnetic wave

What is the relationship between electric field intensity (E) and the electric potential (V)?

A \( E = \frac{1}{4\pi \varepsilon_0} \frac{Q}{r^2} \)
B \( E = – \nabla V \)
C \( E = \frac{Q}{r} \)
D \( E = \nabla V \)

In wave propagation, what is the term for the bending of waves around obstacles or through small openings?

A Reflection
B Refraction
C Diffraction
D Dispersion

What is the speed of electromagnetic waves in a vacuum?

A 300 m/s
B 3 × 10^8 m/s
C 1 × 10^8 m/s
D 3 × 10^6 m/s

What happens to the wavelength of an electromagnetic wave when it enters a medium with a higher refractive index?

A The wavelength increases
B The wavelength decreases
C The wavelength remains the same
D The wavelength becomes zero

What is the primary function of a waveguide?

A To amplify electromagnetic waves
B To direct electromagnetic waves along a specific path
C To store electromagnetic energy
D To reflect waves in multiple directions

What is the primary cause of electromagnetic interference (EMI)?

A The reflection of waves from surfaces
B The emission of electromagnetic waves from external sources
C The absorption of electromagnetic waves by materials
D The diffraction of waves at boundaries

What does the refractive index of a medium describe?

A The ability of a material to absorb electromagnetic radiation
B The speed of light in that medium relative to the speed of light in a vacuum
C The direction of wave propagation
D The resistance to the flow of electric current in the medium

What happens during the reflection of light waves at a boundary?

A The light waves pass through the boundary without any change
B The light waves are absorbed by the boundary
C The light waves are bent at the boundary
D The light waves bounce back at the same angle as the incident angle

Which part of the electromagnetic spectrum has the highest frequency?

A Microwaves
B Infrared
C Ultraviolet
D Gamma rays

What is the phenomenon of polarization in light waves?

A The spreading of light waves through a medium
B The bending of light when it passes through a boundary
C The alignment of the electric field of light in a specific direction
D The absorption of light by materials

What is the relationship between electric field intensity (E) and the electric potential (V)?

A \( E = \frac{1}{4\pi \varepsilon_0} \frac{Q}{r^2} \)
B \( E = – \nabla V \)
C \( E = \frac{Q}{r} \)
D \( E = \nabla V \)

In wave propagation, what is the term for the bending of waves around obstacles or through small openings?

A Reflection
B Refraction
C Diffraction
D Dispersion

What is the primary effect of diffraction in wave propagation?

A Waves pass through a medium at the same speed
B Waves bend around obstacles or spread out after passing through a small opening
C Waves change their direction when they hit a surface
D Waves are absorbed by materials

What is the main function of electromagnetic shielding?

A To amplify signals
B To block or reduce unwanted electromagnetic radiation
C To focus electromagnetic waves
D To reflect electromagnetic waves