Electromagnetic Fields and Waves MCQs (Part-10)

What is the main function of the Poynting vector in electromagnetic waves?

A To represent the direction of wave propagation
B To represent the power flow (energy flux) per unit area of the wave
C To calculate the strength of the magnetic field
D To calculate the electric field intensity

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

A They are inversely proportional to each other
B They are directly proportional to each other
C They are independent of each other
D The frequency determines the speed of the wave

What is the primary role of antennas in communication systems?

A To store electrical energy
B To convert electrical signals into electromagnetic waves for transmission and vice versa
C To reduce the strength of signals
D To filter electromagnetic waves

What is the primary effect of the skin effect in conductors?

A The current tends to flow near the surface of the conductor at higher frequencies
B The current flows equally throughout the conductor
C The current is concentrated in the center of the conductor
D The current increases in the inner layers of the conductor

What does electromagnetic interference (EMI) refer to?

A The unwanted coupling of electromagnetic waves into a system causing disruption
B The reflection of electromagnetic waves
C The generation of electric currents in a conductor
D The reduction of energy in electromagnetic waves

What is the energy density of an electromagnetic wave proportional to?

A The square of the electric field intensity
B The square of the magnetic field intensity
C The square of the wavelength
D The amplitude of the magnetic field

What is the primary role of waveguides in electromagnetic systems?

A To store electromagnetic waves
B To guide and direct electromagnetic waves along a specific path
C To amplify electromagnetic waves
D To filter electromagnetic waves

What is the typical material used for constructing waveguides?

A Non-conductive materials like plastics
B Conductive materials like copper or aluminum
C Magnetic materials like iron
D Insulating materials like glass

What is the primary purpose of using a dielectric material in a capacitor?

A To increase the capacitance
B To reduce the capacitance
C To store energy in the form of a magnetic field
D To conduct electricity

What happens to the wavelength of light when it passes from air into a medium with a higher refractive index?

A It increases
B It decreases
C It remains the same
D It becomes zero

What is the cause of radiation in electromagnetic systems?

A The motion of electrons
B The oscillation of electric and magnetic fields
C The reflection of waves
D The resistance of materials

What does the “cutoff frequency” of a waveguide refer to?

A The maximum frequency that can propagate through the waveguide
B The frequency below which no mode of propagation occurs
C The frequency at which the waveguide is resonant
D The frequency at which the waveguide amplifies signals

What is the primary role of a Faraday cage?

A To block all electromagnetic radiation from entering or leaving a space
B To amplify electromagnetic waves
C To reflect electromagnetic waves
D To store electromagnetic energy

What is the energy density of an electromagnetic wave proportional to?

A The square of the electric field intensity
B The square of the magnetic field intensity
C The square of the wavelength
D The amplitude of the magnetic field

What is the primary effect of the skin effect in conductors?

A The current tends to flow near the surface of the conductor at higher frequencies
B The current flows equally throughout the conductor
C The current is concentrated in the center of the conductor
D The current increases in the inner layers of the conductor

What is the primary characteristic of a resonant cavity in electromagnetic systems?

A It stores electromagnetic energy at a specific frequency
B It amplifies electromagnetic signals
C It reflects electromagnetic waves
D It reduces electromagnetic interference

What is the unit of magnetic flux?

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

What is the role of a dielectric material in an electromagnetic wave system?

A It stores energy in an electric field
B It amplifies electromagnetic waves
C It conducts electricity
D It reflects electromagnetic waves

What is the effect of increasing the frequency of an electromagnetic wave in terms of its energy?

A The energy increases
B The energy remains the same
C The energy decreases
D The energy becomes constant

What is a key factor in determining the performance of an antenna?

A The size of the antenna relative to the wavelength
B The color of the antenna
C The material composition of the antenna
D The power rating of the antenna