This set of Wireless & Mobile Communications Multiple Choice Questions & Answers (MCQs) focuses on “Reflection”.
1. Which of the following mechanism do not impact propagation in mobile communication system?
a) Reflection
b) Diffraction
c) Scattering
d) Refraction
View Answer
Explanation: Reflection, diffraction and scattering are the three basic propagation mechanism which impact propagation in mobile communication system. Large scale propagation model and small scale fading and multipath propagation are described by the physics of reflection, diffraction and scattering.
2. What is the dimension of object as compared to wavelength of propagating wave when reflection occurs?
a) Large
b) Small
c) Same
d) Very small
View Answer
Explanation: Reflection occurs when a propagating electromagnetic wave impinges upon an object which has very large dimensions when compared to the wavelength of the propagation wave. Reflection occurs from the surface of the Earth and from buildings and walls.
3. When does the wave propagating from one medium to another gets partially reflection and partially transmitted?
a) Both mediums have same electrical properties
b) Both mediums have different electrical properties
c) Both mediums have same magnetic properties
d) Both mediums have different magnetic properties
View Answer
Explanation: When a radio wave propagating in one medium impinges upon another medium having different electrical properties. The wave is partially reflected and partially transmitted.
4. What is the case of reflection, in course of second medium being a perfect dielectric?
a) Loss of energy during absorption
b) Total energy reflected back to first medium
c) No loss of energy in absorption
d) Total energy transmitted into second medium
View Answer
Explanation: If the plane wave is incident on a perfect dielectric, part of the energy is transmitted into the second medium and part of the energy is reflected back into the first medium. There is no loss of energy in absorption.
5. What is the case of reflection, in course of second medium being a perfect conductor?
a) Loss of energy during absorption
b) Total energy reflected back to first medium
c) Partly transmission and reflection
d) Total energy transmitted into second medium
View Answer
Explanation: If the second medium is perfect conductor, then all incident energy is reflected back into the second medium. There is no loss of energy during absorption.
6. Which of the following relates the incident and reflected & transmitted wave?
a) Fresnel transmission coefficient
b) Scattering coefficient
c) Diffraction coefficients
d) Fresnel reflection coefficient
View Answer
Explanation: The electric field intensity of the reflected and transmitted waves may be related to the incident waves in the medium of origin through the Fresnel reflection coefficient. It is equal to the ratio of the amplitude of the reflected wave to the incident wave, with each expressed as phasors.
7. Reflection coefficient is not a function of __________
a) Material property
b) Diffraction loss
c) Wave polarization
d) Angle of incidence
View Answer
Explanation: The reflection coefficient is a function of the material properties, and generally depends upon the wave polarization, angle of incidence and frequency of propagating waves. It is a parameter that describes how much of an electromagnetic wave is reflected by an impedance discontinuity in the transmission medium.
8. Polarized wave can be mathematically represented as sum of ________
a) Four orthogonal components
b) Two spatially adjacent components
c) Two spatially orthogonal components
d) Six orthogonal components
View Answer
Explanation: A polarized wave may be mathematically represented as sum of two spatially orthogonal components. For an arbitrary polarization, super position may be used to compute the reflected fields from a reflecting surface.
9. The plane of incidence contains only incident rays.
a) True
b) False
View Answer
Explanation: The plane of incidence is defined as the plane containing the incident, reflected and transmitted waves. The incident light is polarized with its electric field perpendicular to the plane containing the incident, reflected, and refracted rays.
10. Permittivity and conductivity are insensitive to ______ for a good conductor.
a) Operating frequency
b) Polarization density
c) Electric field
d) Property of material
View Answer
Explanation: The terms permittivity and conductivity are insensitive to operating frequency when the material is a good conductor. In the case of conductors, it is evident that electric field inside a conductor is zero. That is because free charges reside only on the surface of conductor and not inside.
11. Velocity of electromagnetic wave can be given by _______
a) 1/√(μ∈)
b) μ/∈
c) 1/(μ∈)
d) μ∈
View Answer
Explanation: For a medium with permittivity, ∈ and permeability, μ the velocity of electromagnetic wave is given by 1/√(μ∈). It is also known as phase velocity. The velocity of light is given by 3*108 m/s.
12. The boundary condition at the surface of incidence obeys ________
a) Kepler’s law
b) Gauss law
c) Faraday law
d) Snell’s law
View Answer
Explanation: Snell’s law is also known as Snell–Descartes law or the law of refraction. It gives a formula to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic media, such as water, glass, or air.
13. The angle at which no reflection occurs in the medium of origin is called _________
a) Azimuth angle
b) Elevation angle
c) Brewster angle
d) Inclination angle
View Answer
Explanation: The Brewster angle is the angle at which no reflection occurs in the medium of origin. It occurs when the incident angle is such that the reflection coefficient is equal to zero. The critical Brewster’s angles for diamond, glass and water are 67.5°, 57° and 53° respectively.
Sanfoundry Global Education & Learning Series – Wireless & Mobile Communications.
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