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The frequency in rad/sec of a wave with velocity of that of light and phase constant of 20 units is (in GHz)
a Explanation: The velocity of a wave is given by V = ω/β. To get ω, put v = 3 x 108 and β= 20. Thus ω = vβ = 3 x 108 x 20 = 60 x 108 = 6 GHz.
a
See lessExplanation: The velocity of a wave is given by V = ω/β. To get ω, put v = 3 x 108 and β= 20. Thus ω = vβ = 3 x 108 x 20 = 60 x 108 = 6 GHz.
Calculate the phase constant of a dielectric with frequency 6 x 106 in air.
c Explanation: The phase constant of a dielectric is given by β = ω√(με). On substituting for ω = 6 x 106, μ = 4π x 10-7, ε = 8.854 x 10-12 in air medium, we get the phase constant as 0.02 units.
c
See lessExplanation: The phase constant of a dielectric is given by β = ω√(με). On substituting
for ω = 6 x 106, μ = 4π x 10-7, ε = 8.854 x 10-12 in air medium, we get the phase constant as 0.02 units.
The attenuation in a good dielectric will be non- zero. State True/False.
a Explanation: Good dielectrics attenuate the electromagnetic waves than any other material. Thus the attenuation constant of the dielectric will be non-zero, positive and large.
a
See lessExplanation: Good dielectrics attenuate the electromagnetic waves than any other
material. Thus the attenuation constant of the dielectric will be non-zero, positive and
large.
The permeability of a dielectric material in air medium will be
a Explanation: The total permeability is the product of the absolute and the relative permeability. In air medium, the relative permeability will be unity. Thus the total permeability is equal to the absolute permeability given by 4π x 10-7 units.
a
See lessExplanation: The total permeability is the product of the absolute and the relative
permeability. In air medium, the relative permeability will be unity. Thus the total
permeability is equal to the absolute permeability given by 4π x 10-7 units.
The total permittivity of a dielectric transformer oil (relative permittivity is 2.2) will be (in order 10-11)
a Explanation: The total permittivity is the product of the absolute and the relative permittivity. The absolute permittivity is 8.854 x 10-12 and the relative permittivity(in this case for transformer oil) is 2.2. Thus the total permittivity is 8.854 x 10-12 x 2.2 = 1.94 x 10-11 units.
a
See lessExplanation: The total permittivity is the product of the absolute and the relative
permittivity. The absolute permittivity is 8.854 x 10-12 and the relative permittivity(in this case for transformer oil) is 2.2. Thus the total permittivity is 8.854 x 10-12 x 2.2 = 1.94 x 10-11 units.
In pure dielectrics, the parameter that is zero is
c Explanation: There are no free charge carriers available in a dielectric. In other words, the charge carriers are present in the valence band, which is very difficult to start to conduct. Thus conduction is low in dielectrics. For pure dielectrics, the conductivity is assumed to be zero.
c
See lessExplanation: There are no free charge carriers available in a dielectric. In other words,
the charge carriers are present in the valence band, which is very difficult to start to
conduct. Thus conduction is low in dielectrics. For pure dielectrics, the conductivity is
assumed to be zero.
The loss tangent of a perfect dielectric will be
d Explanation: Dielectrics have poor conductivity. The loss tangent σ/ωε will be low in dielectrics. For perfect dielectrics, the loss tangent will be minimum.
d
See lessExplanation: Dielectrics have poor conductivity. The loss tangent σ/ωε will be low in
dielectrics. For perfect dielectrics, the loss tangent will be minimum.
The phase shift in the electric and magnetic fields in an EM wave is given by which parameter?
d Explanation: The intrinsic impedance in a conductor is given by η = √(ωμ/2σ) x (1+j). The phase shift is represented by the 1+j term. In polar form it indicates 45 degree phase shift.
d
See lessExplanation: The intrinsic impedance in a conductor is given by η = √(ωμ/2σ) x (1+j).
The phase shift is represented by the 1+j term. In polar form it indicates 45 degree
phase shift.
An example for electromagnetic wave propagation is
c Explanation: The refrigerator, electric fan and relays are electrical devices. They do not use electromagnetic energy as medium of energy transfer. The mobile transponder is an antenna, which uses the EM waves for communication with the satellites.
c
See lessExplanation: The refrigerator, electric fan and relays are electrical devices. They do not use electromagnetic energy as medium of energy transfer. The mobile transponder is an antenna, which uses the EM waves for communication with the satellites.
The propagation constant of the wave in a conductor with air as medium is
a Explanation: The propagation constant is the sum of the attenuation constant and the phase constant. In conductors, the attenuation and phase constant both are same and it is given by √(ωμσ/2). Their sum will be √(ωμσ), is the propagation constant.
a
See lessExplanation: The propagation constant is the sum of the attenuation constant and the
phase constant. In conductors, the attenuation and phase constant both are same and it is given by √(ωμσ/2). Their sum will be √(ωμσ), is the propagation constant.