What is the condition for the reflection of an electromagnetic wave at a boundary?
A Same polarization
B Different impedance
C Same frequency
D Same impedance
Reflection occurs when there is a difference in impedance between two media. When an electromagnetic wave encounters a boundary with different impedance, part of the wave is reflected, and part is transmitted.
What is the effect of polarization on an electromagnetic wave?
A Change in magnetic field strength
B Change in speed
C Change in frequency
D Change in electric field direction
Polarization refers to the orientation of the electric field in an electromagnetic wave. It affects the direction in which the wave oscillates, which can influence how the wave interacts with materials and antennas.
How does the angle of incidence compare to the angle of reflection for an electromagnetic wave?
A Angle of incidence is smaller
B They are always equal
C They are always different
D Angle of reflection is greater
According to the law of reflection, the angle of incidence (the angle the incoming wave makes with the normal) is always equal to the angle of reflection (the angle the reflected wave makes with the normal).
What is the effect of increasing the frequency of a wave on its wavelength in a given medium?
A Increases amplitude
B No change
C Decreases wavelength
D Increases wavelength
In a given medium, as the frequency of an electromagnetic wave increases, its wavelength decreases. This relationship is governed by the equation: c=λ×f, where c is the speed of light, λ is the wavelength, and f is the frequency.
What is the term for the bending of light or waves around obstacles?
A Transmission
B Diffraction
C Reflection
D Polarization
Diffraction occurs when waves encounter an obstacle or pass through an opening, causing them to spread and bend around the edges. This phenomenon is more pronounced when the obstacle’s size is comparable to the wavelength.
Which of these properties of electromagnetic waves can be altered by polarization?
A Electric field direction
B Wavelength
C Speed
D Frequency
Polarization affects the orientation of the electric field in an electromagnetic wave. This property is often used in various applications, such as controlling light direction in optical fibers or reducing glare in sunglasses.
What does the electric field intensity depend on in an electromagnetic wave?
A Wave velocity
B Frequency only
C Magnetic field strength
D Wave amplitude
The electric field intensity in an electromagnetic wave is directly related to the wave’s amplitude. A higher amplitude results in a stronger electric field intensity, which impacts the wave’s energy.
Which condition is required for the transmission of electromagnetic waves through a dielectric material?
A Low permeability
B Low conductivity
C High conductivity
D High permeability
For electromagnetic waves to propagate through a dielectric material, it must have low conductivity, which allows the electric field to penetrate without significant energy dissipation.
Which of the following describes the ability of a material to resist changes in its electric field?
A Conductivity
B Poynting vector
C Permeability
D Permittivity
Permittivity is a property of materials that describes how they respond to an electric field. It quantifies the material’s ability to allow electric field lines to pass through, impacting wave propagation speed.
What happens when an electromagnetic wave is incident at the boundary of two media with different refractive indices?
A The wave disappears
B The wave is absorbed
C The wave refracts and bends
D The wave is completely reflected
When an electromagnetic wave strikes a boundary between two media with different refractive indices, part of the wave is reflected, and part is refracted, bending according to Snell’s law. The amount of bending depends on the difference in refractive indices.
What is the term for the transfer of energy carried by an electromagnetic wave?
A Electric flux
B Poynting vector
C Magnetic flux
D Energy density
The Poynting vector represents the directional energy flux (power per unit area) or energy transfer in an electromagnetic wave. It is calculated as the cross product of the electric and magnetic fields.
What happens when an electromagnetic wave encounters a perfect conductor?
A The wave is reflected
B The wave slows down
C The wave is transmitted
D The wave is absorbed
When an electromagnetic wave encounters a perfect conductor, it is fully reflected. Perfect conductors do not allow electromagnetic waves to penetrate, and they reflect the waves completely.
In which direction do the electric and magnetic fields of a plane electromagnetic wave oscillate relative to each other?
A In phase
B Parallel
C Out of phase
D Perpendicular
In a plane electromagnetic wave, the electric and magnetic fields oscillate perpendicular to each other and to the direction of wave propagation. This is a fundamental characteristic of all electromagnetic waves.
What is the primary role of a boundary condition in wave propagation?
A To polarize waves
B To absorb waves
C To specify field behavior at interfaces
D To reflect waves
Boundary conditions are used to define the behavior of electric and magnetic fields at the interfaces between different media. They are crucial in solving Maxwell’s equations for specific wave propagation problems.
What is the result of increasing the polarization of light?
A Decreased intensity
B Increased intensity
C Increased frequency
D Decreased wavelength
Polarization limits the direction in which light waves can vibrate. When light is fully polarized, the intensity of the transmitted light decreases because only the components of the light wave aligned with the polarizing filter are allowed through.