Electromagnetic Fields and Waves MCQs (Part-13)

What does Gauss’s Law describe in terms of electric fields?

A The relationship between electric fields and charges
B The relationship between electric and magnetic fields
C The relationship between electric potential and electric field
D The relationship between electric field and magnetic field lines

What is the electric field intensity due to a point charge proportional to?

A \( \frac{Q}{r^3} \)
B \( \frac{Q}{r^2} \)
C \( \frac{Q}{r} \)
D \( \frac{1}{r^2} \)

What does the Faraday’s Law of induction describe?

A The relationship between electric fields and current-carrying conductors
B The relationship between time-varying magnetic fields and induced electric fields
C The relationship between electric fields and electric potential
D The relationship between electric field and displacement current

What is the primary role of an antenna in a communication system?

A To store electromagnetic waves
B To convert electrical energy into electromagnetic waves
C To amplify electromagnetic signals
D To direct the electromagnetic waves to a specific location

What is the wave equation for electromagnetic waves in free space?

A \( \nabla^2 E = 0 \)
B \( \nabla^2 E = \mu \varepsilon \frac{\partial^2 E}{\partial t^2} \)
C \( \nabla \times E = \mu \varepsilon \frac{\partial B}{\partial t} \)
D \( E = \frac{Q}{r^2} \)

What is the primary function of waveguides in electromagnetic systems?

A To amplify electromagnetic waves
B To guide electromagnetic waves in a specific direction
C To store electromagnetic energy
D To block unwanted waves

How does an increase in frequency affect the skin effect in conductors?

A It decreases the skin depth
B It increases the skin depth
C It has no effect
D It causes the current to spread evenly throughout the conductor

What is the effect of a dielectric material on the speed of light in a medium?

A It decreases the speed of light
B It increases the speed of light
C It has no effect
D It causes the light to bend

What is the unit of energy density in an electromagnetic wave?

A Joules per cubic meter (J/m³)
B Ampere-Turns per meter (A/m)
C Tesla (T)
D Weber (Wb)

What is the primary cause of electromagnetic radiation from an antenna?

A Oscillating electric and magnetic fields
B The movement of charges in the antenna
C The reflection of waves from the antenna surface
D The change in frequency of waves

What is the primary characteristic of the electromagnetic spectrum?

A It includes only visible light
B It includes all types of electromagnetic radiation
C It includes only high-frequency waves
D It includes only low-frequency waves

What is the cause of diffraction in wave propagation?

A The wave bends around obstacles or passes through small openings
B The wave slows down as it passes through a medium
C The wave is absorbed by a material
D The wave reflects off surfaces

What is the wave equation for electromagnetic waves in free space?

A \( \nabla^2 E = 0 \)
B \( \nabla^2 E = \mu \varepsilon \frac{\partial^2 E}{\partial t^2} \)
C \( \nabla \times E = \mu \varepsilon \frac{\partial B}{\partial t} \)
D \( E = \frac{Q}{r^2} \)

What is the primary function of waveguides in electromagnetic systems?

A To amplify electromagnetic waves
B To guide electromagnetic waves in a specific direction
C To store electromagnetic energy
D To block unwanted waves

How does an increase in frequency affect the skin effect in conductors?

A It decreases the skin depth
B It increases the skin depth
C It has no effect
D It causes the current to spread evenly throughout the conductor

What is the effect of a dielectric material on the speed of light in a medium?

A It decreases the speed of light
B It increases the speed of light
C It has no effect
D It causes the light to bend

What is the primary characteristic of the electromagnetic spectrum?

A It includes only visible light
B It includes all types of electromagnetic radiation
C It includes only high-frequency waves
D It includes only low-frequency waves

What is the cause of diffraction in wave propagation?

A The wave bends around obstacles or passes through small openings
B The wave slows down as it passes through a medium
C The wave is absorbed by a material
D The wave reflects off surfaces

What is the wave equation for electromagnetic waves in free space?

A \( \nabla^2 E = 0 \)
B \( \nabla^2 E = \mu \varepsilon \frac{\partial^2 E}{\partial t^2} \)
C \( \nabla \times E = \mu \varepsilon \frac{\partial B}{\partial t} \)
D \( E = \frac{Q}{r^2} \)

What is the primary function of waveguides in electromagnetic systems?

A To amplify electromagnetic waves
B To guide electromagnetic waves in a specific direction
C To store electromagnetic energy
D To block unwanted waves