Electrical Engineering MCQs (Part-41)

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

What is the unit of electric field intensity (E)?

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

What is the primary use of Gauss’s Law in electromagnetics?

A To calculate the electric field due to charge distributions
B To calculate the magnetic field due to current-carrying conductors
C To determine the velocity of electromagnetic waves
D To compute the energy density in an electromagnetic field

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 does the magnetic field intensity (H) measure in electromagnetics?

A The strength of the electric field
B The strength of the magnetic field created by current-carrying conductors
C The force acting on a moving charge
D The magnetic flux through a surface

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

A To convert electrical energy into electromagnetic waves
B To store 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 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 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 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 a 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 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 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 a 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 effect 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 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 unchanged
D The wavelength becomes zero

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 a 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 happens to the energy of an electromagnetic wave when its frequency is increased?

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

What is the main function of a step-up transformer in a transmission system?

A To increase current
B To increase voltage
C To decrease frequency
D To convert AC to DC

Which material is most commonly used for overhead transmission line conductors?

A Copper
B Aluminum
C Iron
D Steel

What is the purpose of insulators in overhead transmission lines?

A To conduct electricity
B To prevent current leakage
C To reduce power losses
D To provide mechanical support

What is the main cause of sag in overhead transmission lines?

A Excessive current
B Weight of the conductor
C High wind pressure
D Low voltage

What type of cable is most suitable for underground power distribution?

A Overhead conductor
B XLPE cable
C Twisted pair cable
D Coaxial cable

What is the typical range of voltage for low-voltage distribution systems?

A 0-1 kV
B 1-10 kV
C 10-30 kV
D Above 30 kV

What is the purpose of a substation in a distribution system?

A To generate electricity
B To step down voltage levels for distribution
C To transmit electricity over long distances
D To store energy

Which phenomenon is responsible for the power loss and noise in overhead lines?

A Eddy currents
B Corona discharge
C Skin effect
D Electromagnetic induction

Why are transmission lines typically operated at high voltage?

A To increase current flow
B To reduce transmission losses
C To improve insulation
D To increase frequency

Which device is used to protect a distribution system from lightning strikes?

A Circuit breaker
B Surge arrester
C Fuse
D Transformer

What is the function of a step-down transformer in a distribution system?

A To increase voltage
B To decrease voltage
C To improve frequency
D To store energy

What is the primary function of an earthing system in power distribution?

A To increase voltage
B To ensure safety and fault current dissipation
C To reduce resistance
D To improve power factor

What is the key disadvantage of underground cables compared to overhead lines?

A Higher resistance
B Higher initial cost
C More transmission losses
D Less reliable

Which factor primarily determines the selection of conductor size in a transmission line?

A Voltage rating
B Current carrying capacity
C Length of the line
D Sag

What is the purpose of voltage regulation in a distribution system?

A To maintain constant frequency
B To maintain voltage levels within permissible limits
C To stabilize load demand
D To reduce energy losses

What is the primary function of a capacitor bank in a distribution system?

A Voltage step-up
B Power factor improvement
C Current regulation
D Fault detection

What is the main advantage of using high-voltage DC (HVDC) for long-distance transmission?

A Simpler design
B Elimination of reactive power losses
C Increased frequency
D Reduced earthing requirements

What is the term for the horizontal distance between two adjacent overhead conductors?

A Span
B Conductor spacing
C Clearance
D Tension

Which device automatically disconnects the power supply in case of overload?

A Circuit breaker
B Transformer
C Capacitor
D Lightning arrester

What is the effect of increasing the length of a transmission line on its impedance?

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