InterviewSolution

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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

101.	Calculate the wavelength of the wave with phase constant of 3.14 units.(a) 1(b) 2(c) 0.5(d) 4I got this question in an interview.This question is from Dielectric vs Conductor Wave Propagation in division EM Wave Propagation of Electromagnetic Theory
Answer» Correct OPTION is (b) 2 Easiest explanation: The wavelength is the ratio of 2π to the phase CONSTANT β. On SUBSTITUTING for β = 3.14, we GET λ = 2π/β = 2π/3.14 = 2 UNITS.

102.	In conductors, which two parameters are same?(a) Wavelength and phase constant(b) Phase and attenuation constant(c) Attenuation constant and skin depth(d) Skin depth and wavelengthThis question was posed to me during an interview.My question is taken from Dielectric vs Conductor Wave Propagation topic in section EM Wave Propagation of Electromagnetic Theory
Answer» Right option is (B) Phase and attenuation CONSTANT The explanation is: In CONDUCTORS, which are CONSIDERED to be lossy, the attenuation and the phase constant are the same. It is given by α=β= √(ωμσ/2).

103.	In conductors, which condition will be true?(a) σ/ωε > 1(b) σωε > 1(c) σ/ωε < 1(d) σωε < 1The question was asked in an online interview.Asked question is from Dielectric vs Conductor Wave Propagation topic in division EM Wave Propagation of Electromagnetic Theory
Answer» CORRECT answer is (a) σ/ωε > 1 The explanation is: For CONDUCTORS, the CONDUCTIVITY will be maximum. Thus the loss tangent is GREATER than UNITY. This is given by σ/ωε >1.

104.	An example for lossless propagation is(a) Dielectric waveguide propagation(b) Conductor propagation(c) Cavity resonator propagation(d) It is not possibleThis question was posed to me during an online interview.This interesting question is from Lossy and Lossless Dielectrics topic in chapter EM Wave Propagation of Electromagnetic Theory
Answer» The CORRECT option is (d) It is not possible To elaborate: There are many techniques employed to ACHIEVE zero attenuation or MAXIMUM propagation. But it is not achievable PRACTICALLY. THUS lossless propagation is not possible practically.

105.	Calculate the phase constant of a wave with skin depth of 2.5 units.(a) 5/2(b) 5(c) 2(d) 2/5This question was addressed to me in a national level competition.Question is from Lossy and Lossless Dielectrics in division EM Wave Propagation of Electromagnetic Theory
Answer» RIGHT choice is (d) 2/5 Easiest explanation: The SKIN depth is the reciprocal of the PHASE CONSTANT and the attenuation constant too. Thus δ = 1/β. On substituting for δ = 2.5, we get β = 1/δ = 1/2.5 = 2/5 units.

106.	Calculate the skin depth of a material with attenuation constant of 2 units.(a) 2(b) 1(c) 0.5(d) 4I got this question during an internship interview.My doubt stems from Lossy and Lossless Dielectrics in portion EM Wave Propagation of Electromagnetic Theory
Answer» Correct choice is (c) 0.5 To explain: The skin depth of a MATERIAL is the reciprocal of the ATTENUATION CONSTANT. Thus δ = 1/α. On SUBSTITUTING for α = 2, we GET δ = ½ = 0.5 units.

107.	The intrinsic impedance is the ratio of square root of(a) Permittivity to permeability(b) Permeability to permittivity(c) Phase constant to wavelength(d) Wavelength to phase constantI got this question during an interview.I need to ask this question from Lossy and Lossless Dielectrics topic in section EM Wave Propagation of Electromagnetic Theory
Answer» Right CHOICE is (B) Permeability to permittivity To explain: The INTRINSIC IMPEDANCE is the impedance of a particular material. It is the ratio of square root of the permeability to permittivity. For air, the intrinsic impedance is 377 ohm or 120π.

108.	In lossy dielectric, the phase difference between the electric field E and the magnetic field H is(a) 90(b) 60(c) 45(d) 0This question was addressed to me in exam.I'd like to ask this question from Lossy and Lossless Dielectrics in chapter EM Wave Propagation of Electromagnetic Theory
Answer» Right OPTION is (d) 0 Explanation: In a lossy DIELECTRIC, the E and H component will be in PHASE. This implies that the phase difference between E and H will be 0.

109.	Which of the following is the correct relation between wavelength and the phase constant of a wave?(a) Phase constant = 2π/wavelength(b) Phase constant = 2π x wavelength(c) Phase constant = 1/(2π x wavelength)(d) Phase constant = wavelength/2πThe question was asked by my school teacher while I was bunking the class.This key question is from Lossy and Lossless Dielectrics in portion EM Wave Propagation of Electromagnetic Theory
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110.	Calculate the velocity of a wave with frequency 2 x10^9 rad/s and phase constant of 4 x 10^8 units.(a) 0.5(b) 5(c) 0.2(d) 2I have been asked this question during an internship interview.Question is taken from Lossy and Lossless Dielectrics topic in section EM Wave Propagation of Electromagnetic Theory
Answer» Right CHOICE is (b) 5 To explain I would SAY: The VELOCITY of a wave is the ratio of the FREQUENCY to the phase constant. Thus V = ω/β. On substituting the given values, we get V = 2 x10^9/ 4 x 10^8 = 5 UNITS.

111.	For a lossless dielectric, the attenuation will be(a) 1(b) 0(c) -1(d) InfinityI have been asked this question in class test.This interesting question is from Lossy and Lossless Dielectrics topic in division EM Wave Propagation of Electromagnetic Theory
Answer» Correct answer is (b) 0 Easiest EXPLANATION: The attenuation is the loss of power of the wave during its propagation. In a lossless DIELECTRIC, the loss of power will not OCCUR. THUS the attenuation will be zero.

112.	Calculate the phase constant of a wave with frequency 12 rad/s and velocity 3×10^8 m/s(in 10^-8 order)(a) 0.5(b) 72(c) 4(d) 36This question was posed to me during an interview for a job.The query is from Lossy and Lossless Dielectrics in chapter EM Wave Propagation of Electromagnetic Theory
Answer» CORRECT answer is (c) 4 The best explanation: The phase constant is GIVEN by β = ω√(με), where ω is the FREQUENCY in rad/s and 1/√(με) is the velocity of WAVE. On substituting √(με) = 3×10^8 and ω = 12, we get β = 12/(3×10^8) = 4 x 10^-8m/s.

113.	For a perfect dielectric, which parameter will be zero?(a) Conductivity(b) Frequency(c) Permittivity(d) PermeabilityThis question was addressed to me in exam.Enquiry is from Lossy and Lossless Dielectrics in section EM Wave Propagation of Electromagnetic Theory
Answer» Right option is (a) CONDUCTIVITY For EXPLANATION I WOULD say: The conductivity will be minimum for a DIELECTRIC. For a perfect dielectric, the conductivity will be zero.

114.	For a dielectric, the condition to be satisfied is(a) σ/ωε > 1(b) σ/ωε < 1(c) σ = ωε(d) ωε = 1I had been asked this question in an international level competition.This intriguing question originated from Lossy and Lossless Dielectrics topic in portion EM Wave Propagation of Electromagnetic Theory
Answer» Correct CHOICE is (b) σ/ωε < 1 To elaborate: In a dielectric, the conductivity will be very less. Thus the LOSS tangent will be less than unity. This IMPLIES σ/ωε < 1 is true.

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