Electromagnetic Fields and Waves MCQs (Part-5)

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

A The electric field is proportional to the derivative of the potential.
B The electric field is inversely proportional to the potential.
C The electric field is independent of the potential.
D The electric field is equal to the potential.

What does Maxwell’s third equation (Ampere’s Law with Maxwell’s correction) relate to?

A The relationship between electric fields and charge
B The relationship between electric currents and magnetic fields
C The relationship between electric fields and changing magnetic fields
D The relationship between electric potential and current

Which of the following statements is true for electromagnetic waves in a vacuum?

A They require a medium to propagate
B They cannot travel through empty space
C They propagate at the speed of light
D Their speed is reduced in a vacuum

What is the unit of magnetic flux density (B)?

A Ampere-Turns per meter (A/m)
B Weber per meter squared (Wb/m²)
C Volt per meter (V/m)
D Tesla (T)

Which equation describes the electric field of a point charge?

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

What is the principle of superposition in electromagnetics?

A The total field is the sum of individual fields, even if they are of the same type
B The total field is the product of individual fields
C The total field cancels out individual fields
D The total field is the difference between individual fields

What is the effect of increasing the frequency of an electromagnetic wave on its wavelength?

A The wavelength increases
B The wavelength decreases
C The wavelength stays the same
D The wavelength becomes constant at high frequencies

What is the primary function of a Faraday cage?

A To reflect electromagnetic waves
B To block all electromagnetic waves from entering or exiting a space
C To amplify electromagnetic waves
D To generate electromagnetic fields

What is the magnetic force on a moving charge proportional to?

A The electric field strength
B The velocity of the charge
C The charge squared
D The time of travel

What does the Poynting vector represent in electromagnetics?

A The direction of wave propagation
B The energy flux or power per unit area carried by an electromagnetic wave
C The magnetic field intensity
D The electric field intensity

Which of the following is a property of electromagnetic waves?

A They can travel only through solids
B They travel at different speeds in a vacuum depending on the frequency
C They carry both electric and magnetic energy
D They require a medium to propagate

What is the phase difference between the electric field and magnetic field in an electromagnetic wave?

A 90 degrees
B 180 degrees
C 0 degrees
D They are in opposite phases

What is the unit of electric field intensity?

A Ampere per meter (A/m)
B Volt per meter (V/m)
C Ohm (Ω)
D Tesla (T)

What is the primary function of a waveguide?

A To amplify signals
B To direct electromagnetic waves along a specific path
C To store electromagnetic energy
D To convert electrical signals into electromagnetic waves

What is the effect of increasing the temperature on the skin effect in conductors?

A The skin depth increases
B The skin depth decreases
C The skin effect disappears
D The current becomes uniform throughout the conductor

What is the primary characteristic of electromagnetic radiation?

A Charges accelerating or decelerating generate both electric and magnetic fields
B Electromagnetic waves are created by stationary charges
C Electromagnetic radiation occurs when charges are at rest
D Magnetic fields generate electric fields in a conductor

Which type of electromagnetic wave has the longest wavelength?

A Gamma rays
B X-rays
C Radio waves
D Microwaves

What is the primary characteristic of the electromagnetic spectrum?

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

What is the role of the magnetic field in the operation of an electric motor?

A To store energy
B To induce an electric current
C To generate an oscillating field
D To interact with current-carrying conductors to produce motion

What is the relationship between wavelength and frequency in an electromagnetic wave?

A Wavelength is directly proportional to frequency
B Wavelength is inversely proportional to frequency
C Wavelength is equal to frequency
D Wavelength is unrelated to frequency