129 + Interview Questions in Transmission Lines in Electromagnetic Theory Page 2 InterviewSolution

51.	The skin depth is used to find which parameter?(a) DC resistance(b) AC resistance(c) Permittivity(d) PotentialThis question was posed to me by my school principal while I was bunking the class.My doubt is from Skin Effect topic in chapter Transmission Lines of Electromagnetic Theory
Answer» CORRECT CHOICE is (b) AC RESISTANCE The best EXPLANATION: Since the skin depth varies for different frequencies, it can be used to calculate the varying AC resistance for a material.

Discussion

52.	The skin effect is a phenomenon observed in(a) Insulators(b) Dielectrics(c) Conductors(d) SemiconductorsThe question was asked in an international level competition.My question comes from Skin Effect in section Transmission Lines of Electromagnetic Theory
Answer» CORRECT CHOICE is (c) Conductors Easiest explanation: The skin of the conductor allows a certain AMOUNT of ELECTROMAGNETIC power to pass through it. This PHENOMENON is called the skin effect. This is the reason why, electromagnetic waves cannot travel inside a conductor.

Discussion

53.	The transmission coefficient of a wave travelling through two media having electric intrinsic impedances of 3 and 2 respectively is(a) ^2⁄2(b) ^8⁄9(c) ^4⁄5(d) ^1⁄4The question was posed to me by my college professor while I was bunking the class.Question is from Intrinsic Impedance and Propagation Constant topic in division Transmission Lines of Electromagnetic Theory
Answer» RIGHT answer is (c) ^4⁄5 Explanation: The transmission coefficient in TERMS for intrinsic IMPEDANCE is R = 2η2/η2 + η1. On substituting the given DATA, we get R = 2 X 2/2 + 3 = 4/5.

Discussion

54.	The reflection coefficient of a wave travelling through two media having magnetic intrinsic impedances of 2 and 1 respectively is(a) ^1⁄2(b) ^1⁄3(c) ^1⁄4(d) ^1⁄5This question was addressed to me in a national level competition.My enquiry is from Intrinsic Impedance and Propagation Constant in division Transmission Lines of Electromagnetic Theory
Answer» The correct choice is (b) ^1⁄3 Explanation: The reflection coefficient in terms for MAGNETIC INTRINSIC impedance is R = η1 – η2/η1 + η2. On SUBSTITUTING the given data, we GET R = 2 – 1/2 + 1 = 1/3.

Discussion

55.	The reflection coefficient of a wave travelling through two media having electric intrinsic impedances of 3 and 5 respectively is(a) 2(b) 8(c) ^5⁄3(d) 1/4This question was posed to me in quiz.Query is from Intrinsic Impedance and Propagation Constant in section Transmission Lines of Electromagnetic Theory
Answer» CORRECT option is (d) 1/4 Easy explanation: The REFLECTION coefficient in terms for intrinsic IMPEDANCE is R= η2-η1/η2+η1. On substituting the given data, we get R = 5 – 3/5 + 3 = 2/8 = ¼.

Discussion

56.	The standing wave ratio of a wave travelling through two media having intrinsic impedances of 3 and 2 is(a) ^2⁄3(b) ^3⁄2(c) ^1⁄5(d) 5I have been asked this question during an online exam.Query is from Intrinsic Impedance and Propagation Constant topic in section Transmission Lines of Electromagnetic Theory
Answer» The correct OPTION is (B) ^3⁄2 Best explanation: The standing wave ratio is given by the ratio of the intrinsic impedance of medium 1 to the intrinsic impedance of medium 2. THUS S = η1/η2. On substituting for η1 = 3 and η2 = 2, we GET S = 3/2.

Discussion

57.	The standing wave ratio of the wave with maximum and minimum electric field intensities of 12 and 4 is(a) 12(b) 4(c) 3(d) 48I have been asked this question in an interview for internship.Origin of the question is Intrinsic Impedance and Propagation Constant in section Transmission Lines of Electromagnetic Theory
Answer» Right choice is (C) 3 Explanation: The SWR is DEFINED as the RATIO of maximum electric FIELD intensities to the minimum field intensities. It is given by S = EMAX/EMIN. Thus for the given data, S = 12/4 = 3.

Discussion

58.	Calculate the propagation constant of a wave with impedance and admittance given by 32 and 12 respectively.(a) 19.6(b) 17.6(c) 15.6(d) 13.6This question was posed to me in a national level competition.I need to ask this question from Intrinsic Impedance and Propagation Constant topic in section Transmission Lines of Electromagnetic Theory
Answer» The correct option is (a) 19.6 Best explanation: The propagation constant is given by γ = √(ZY), where Z is the IMPEDANCE and Y is the admittance. On SUBSTITUTING for Z = 32 and Y = 12,we GET γ = 19.6 UNITS.

Discussion

59.	The intrinsic impedance in free space is(a) 60π(b) 12π(c) 6π(d) 120πI have been asked this question in examination.My question is from Intrinsic Impedance and Propagation Constant in portion Transmission Lines of Electromagnetic Theory
Answer» Right answer is (d) 120π Easy explanation: The intrinsic IMPEDANCE of the free space is the RATIO of the permittivity to the permeability. For air medium, the VALUE is 120π or 377 ohm.

Discussion

60.	The intrinsic angle is 25^0, find the loss angle.(a) 12.5(b) 50(c) 25(d) 75This question was posed to me at a job interview.This key question is from Intrinsic Impedance and Propagation Constant topic in chapter Transmission Lines of Electromagnetic Theory
Answer» The CORRECT option is (b) 50 The EXPLANATION is: The LOSS ANGLE is twice of the intrinsic angle. It is given by δ = 2θn. On substituting for θn = 25, the loss angle δ = 2(25) = 50 degree.

Discussion

61.	The propagation constant is a complex quantity. State true/false.(a) True(b) FalseThe question was posed to me by my school teacher while I was bunking the class.I'd like to ask this question from Intrinsic Impedance and Propagation Constant topic in chapter Transmission Lines of Electromagnetic Theory
Answer» RIGHT option is (a) True Best explanation: The PROPAGATION constant is a complex QUANTITY. It is given by γ = α + jβ, where α is the attenuation constant, a real value and β is the PHASE constant, a complex value.

Discussion

62.	The intrinsic impedance is defined as the ratio of the magnetic field to the electric field of the electromagnetic wave. State true/false(a) True(b) FalseI had been asked this question in an interview for internship.The query is from Intrinsic Impedance and Propagation Constant topic in portion Transmission Lines of Electromagnetic Theory
Answer» Right choice is (b) False For EXPLANATION: The intrinsic IMPEDANCE is defined as the ratio of the electric field intensity to the MAGNETIC field intensity. It is denoted by η. It is a COMPLEX quantity.

Discussion

63.	The intrinsic impedance of a wave with electric and magnetic field of 10 and 8 respectively is(a) 1.6(b) 1.11(c) 1.25(d) 0.8The question was asked in homework.The question is from Intrinsic Impedance and Propagation Constant topic in division Transmission Lines of Electromagnetic Theory
Answer» Correct choice is (B) 1.11 The explanation is: The intrinsic impedance of a WAVE is GIVEN by η = √(E/H). on substituting for E = 10 and H = 8, we get η = 1.11 UNITS.

Discussion

64.	The standing wave ratio ofshort circuited and open circuited lines will be(a) 0(b) 1(c) -1(d) ∞I have been asked this question in my homework.The above asked question is from Standing Waves and SWR in division Transmission Lines of Electromagnetic Theory
Answer» The correct answer is (d) ∞ To explain I would say: The TRANSMISSION line will reflect high POWER when it is short or circuited. This will lead to high reflection coefficient. THUS the STANDING wave ratio will be infinity for these extreme CASES.

Discussion

65.	The minimum impedance of a 75 ohm transmission line with a SWR of 2.5 is(a) 100(b) 50(c) 25(d) 30I had been asked this question by my school teacher while I was bunking the class.Query is from Standing Waves and SWR topic in section Transmission Lines of Electromagnetic Theory
Answer» Correct option is (d) 30 The explanation: The minimum IMPEDANCE in terms of SWR is GIVEN by ZMIN = Zo/S.Substituting the given DATA for S = 2.5 and Zo = 75, we GET Zmin = 75/2.5 = 30.

Discussion

66.	The maximum impedance of a 50 ohm transmission line with SWR of 3 is(a) 50/3(b) 3/50(c) 150(d) 450The question was asked in final exam.This interesting question is from Standing Waves and SWR in section Transmission Lines of Electromagnetic Theory
Answer» The correct option is (c) 150 The explanation: The MAXIMUM impedance is given by the product of the characteristic impedance and the SWR. Thus Zmax = S Zo. On SUBSTITUTING for S = 3 and Zo = 50, we get ZMAX = 3 X 50 = 150 UNITS.

Discussion

67.	For matched line, the standing wave ratio will be(a) 0(b) ∞(c) -1(d) 1I had been asked this question in examination.My question comes from Standing Waves and SWR topic in division Transmission Lines of Electromagnetic Theory
Answer» The correct answer is (d) 1 Easy explanation: In a matched line, maximum transmission occurs. The REFLECTION will be zero. The standing WAVE RATIO S = 1 – R/1 + R. For R = 0, the SWR is unity for matched line.

Discussion

68.	The range of the standing wave ratio is(a) 0 < S < 1(b) -1 < S < 1(c) 1 < S < ∞(d) 0 < S < ∞This question was posed to me in exam.The query is from Standing Waves and SWR in portion Transmission Lines of Electromagnetic Theory
Answer» The correct OPTION is (c) 1 < S < ∞ Easiest explanation: The standing wave ratio is GIVEN by S = 1 – R/1 + R. Thus the minimum VALUE of S is 1. It can EXTEND upto infinity for long lines. Thus the range is 1 < S < ∞.

Discussion

69.	Find the reflection coefficient of the wave with SWR of 3.5.(a) 0.55(b) 0.23(c) 0.48(d) 0.68This question was posed to me during an interview.Enquiry is from Standing Waves and SWR in section Transmission Lines of Electromagnetic Theory
Answer» The CORRECT answer is (a) 0.55 Easy explanation: The reflection coefficient in TERMS of the SWR is GIVEN by R = S – 1/S + 1. On substituting for S = 3.5, we get 3.5 – 1/3.5 + 1 = 0.55.

Discussion

70.	Find the standing wave ratio, when a load impedance of 250 ohm is connected to a 75 ohm line.(a) 0.3(b) 75(c) 250(d) 3.33I have been asked this question in class test.This interesting question is from Standing Waves and SWR topic in chapter Transmission Lines of Electromagnetic Theory
Answer» Right option is (d) 3.33 To EXPLAIN I would say: The standing wave RATIO is the ratio of the LOAD impedance to the characteristic impedance. Thus S = ZL/ZO. On substituting for ZL = 250 and Zo = 75, we GET S = 250/75 = 3.33.

Discussion

71.	The maxima and minima voltage of the standing wave are 6 and 2 respectively. The standing wave ratio is(a) 2(b) 3(c) 1/2(d) 4This question was posed to me by my school principal while I was bunking the class.My question comes from Standing Waves and SWR in portion Transmission Lines of Electromagnetic Theory
Answer» Correct choice is (b) 3 Easy EXPLANATION: The ratio of voltage maxima to voltage MINIMA is given by the standing wave ratio SWR. THUS S = VMAX/VMIN. On SUBSTITUTING the given DATA, we get S = 6/2 = 3.

Discussion

72.	Given that the reflection coefficient is 0.6. Find the SWR.(a) 2(b) 4(c) 6(d) 8I have been asked this question during an interview for a job.Query is from Standing Waves and SWR in division Transmission Lines of Electromagnetic Theory
Answer» Right OPTION is (b) 4 To explain: The RELATION between reflection coefficient and SWR is given by S = 1 + R/1 – R. On SUBSTITUTING for R = 0.6, we get S = 1 + 0.6/1 – 0.6 = 1.6/0.4 = 4.

Discussion

73.	Standing wave ratio is defined as the(a) Ratio of voltage maxima to voltage minima(b) Ratio of current maxima to current minima(c) Product of voltage maxima and voltage minima(d) Product of current maxima and current minimaThe question was asked in an internship interview.The origin of the question is Standing Waves and SWR topic in section Transmission Lines of Electromagnetic Theory
Answer» Right answer is (a) RATIO of voltage maxima to voltage minima For explanation: SWR is defined as the ratio of the partial standing WAVE’s amplitude at an antinode (maximum) to the amplitude at a node (MINIMUM) along the LINE. It is GIVEN by S = VMAX/VMIN.

Discussion

74.	The transmitted power in a transmission line, when the reflection coefficient and the incident power are 0.6 and 24V respectively, is(a) 15.36(b) 51.63(c) 15.63(d) 51.36I got this question during an interview.My question is from Reflection and Transmission Coefficients topic in portion Transmission Lines of Electromagnetic Theory
Answer» Correct ANSWER is (a) 15.36 For EXPLANATION: The TRANSMITTED power in terms of the reflection coefficient and the incident power is Ptr = (1-R^2)Pinc, where R = 0.6 and Pinc = 24, from the given data. Thus Ptr = (1- 0.6^2) x 24 = 15.36 units.

Discussion

75.	Standing waves occurs due to(a) Impedance match(b) Impedance mismatch(c) Reflection(d) TransmissionI have been asked this question by my college director while I was bunking the class.Asked question is from Standing Waves and SWR in section Transmission Lines of Electromagnetic Theory
Answer» Right answer is (B) Impedance mismatch For EXPLANATION: Impedance mismatches result in standing waves along the transmission line. It SHOWS the variation of the WAVE AMPLITUDES due to mismatching.

Discussion

76.	Find the power reflected in a transmission line, when the reflection coefficient and input power are 0.45 and 18V respectively.(a) 3.645(b) 6.453(c) 4.563(d) 5.463I have been asked this question during an online interview.This question is from Reflection and Transmission Coefficients topic in chapter Transmission Lines of Electromagnetic Theory
Answer» CORRECT choice is (a) 3.645 Explanation: The ratio of the reflected to incident amplitudes gives the reflection. Similarly, the ratio of reflected to incident power gives square of the reflection COEFFICIENT. Thus Prefl = R^2Pinc. On substituting for R = 0.45 and Pinc = 18, we get Prefl = 0.45^2 x 18 = 3.645 units.

Discussion

77.	In matched line, the transmission coefficient is(a) 0(b) 1(c) -1(d) InfinityThe question was asked by my college professor while I was bunking the class.My question is based upon Reflection and Transmission Coefficients in division Transmission Lines of Electromagnetic Theory
Answer» Right option is (b) 1 Explanation: In matched line, the MAXIMUM power is transferred from transmitter to receiver. Such REFLECTION COEFFICIENT will be zero and TRANSMISSION coefficient is UNITY.

Discussion

78.	The transmission coefficient in a wave travelling through two media having permittivities 4 and 1 is(a) 1/4(b) 3/2(c) 3/4(d) 2/3I got this question during an online interview.Origin of the question is Reflection and Transmission Coefficients in chapter Transmission Lines of Electromagnetic Theory
Answer» Correct ANSWER is (d) 2/3 The BEST EXPLANATION: The transmission coefficient in terms of the permittivity is given by T= 2√ε2/√ε1 + √ε2. On SUBSTITUTING for ε1 = 4 and ε2 = 1, we get T= 2(1)/1 + 2 = 2/3.

Discussion

79.	The reflection coefficient of a transmission line having characteristic and load impedances as 50 and 30 ohm respectively is(a) 1/4(b) 1/8(c) 1/2(d) 3/4This question was posed to me by my school teacher while I was bunking the class.Question is taken from Reflection and Transmission Coefficients topic in chapter Transmission Lines of Electromagnetic Theory
Answer» Correct ANSWER is (a) 1/4 The EXPLANATION: The reflection coefficient of a transmission line is givenby, R = ZL – ZO/ZL + Zo, where ZL and Zo is the load and characteristic impedances RESPECTIVELY. On SUBSTITUTING ZL = 30 and Zo = 50, the reflection coefficient R = 50 – 30/50 + 30 = 20/80 = 1/4.

Discussion

80.	The transmission coefficient in a wave travelling through two media having intrinsic impedances of 5.5 and 1.33 is(a) 0.389(b) 0.55(c) 0.133(d) 0.42This question was posed to me during an interview.This question is from Reflection and Transmission Coefficients in chapter Transmission Lines of Electromagnetic Theory
Answer» The correct ANSWER is (a) 0.389 To explain: The transmission coefficient is terms of the INTRINSIC impedance is given by T = 2η2/η1 + η2. On SUBSTITUTING for η1 = 5.5 and η2 = 1.33, we GET T = 2 x 1.33/1.33 + 5.5 = 2.66/6.83 = 0.389.

Discussion

81.	Calculate the transmission coefficient, when the incident and transmitted amplitudes are 10 and 7 respectively.(a) 17(b) 3(c) 10/7(d) 0.7I got this question by my college director while I was bunking the class.My enquiry is from Reflection and Transmission Coefficients in division Transmission Lines of Electromagnetic Theory
Answer» Correct answer is (d) 0.7 The best I can EXPLAIN: The transmission coefficient is defined as the ratio of the transmitted AMPLITUDE to the incident amplitude. THUS T = ET/Ei. On substituting for Ei = 10 and Et = 7, we get T = 7/10 = 0.7.

Discussion

82.	The incident wave amplitude is 24 units. Find the reflected wave amplitude if the reflection coefficient is 0.6.(a) 14.4(b) 16.6(c) 13.3(d) 11.1I got this question in final exam.I would like to ask this question from Reflection and Transmission Coefficients in chapter Transmission Lines of Electromagnetic Theory
Answer» Correct answer is (a) 14.4 Best explanation: The reflection coefficient is the RATIO of the reflected amplitude to the incident amplitude. THUS R = Er/EI. On substituting for Ei = 24 and R = 0.6, we GET Er = R Ei = 0.6 X 24 = 14.4 units.

Discussion

83.	The reflection coefficient of a wave travelling through two media having permittivities 4 and 9 respectively is(a) 0(b) 0.5(c) 0.25(d) 0.2This question was posed to me in an interview.This is a very interesting question from Reflection and Transmission Coefficients in division Transmission Lines of Electromagnetic Theory
Answer» The correct choice is (d) 0.2 For EXPLANATION: The reflection COEFFICIENT in terms of permittivity is given by R = √ε2 – √ε1/√ε2 + √ε1. On substituting for ε1 = 4 and ε2 = 9, we GET R = 3 – 2/3 + 2 = 1/5 = 0.2.

Discussion

84.	The reflection coefficient of a wave with transmission coefficient 0.35 is(a) 1.35(b) 0.65(c) 0.35(d) 0.7This question was posed to me during an online interview.The query is from Reflection and Transmission Coefficients in division Transmission Lines of Electromagnetic Theory
Answer» The CORRECT answer is (b) 0.65 Easy EXPLANATION: The reflection COEFFICIENT is the reverse of the transmission coefficient. Thus T + R = 1. On substituting for T = 0.35, the reflection coefficient R will be 1 – 0.35 = 0.65 (no UNIT).

Discussion

85.	Find the reflection coefficient of the wave passing through two media having intrinsic impedances of 4 and 9 respectively.(a) 0.5(b) 1(c) 0.38(d) 0.1The question was asked in semester exam.I want to ask this question from Reflection and Transmission Coefficients topic in division Transmission Lines of Electromagnetic Theory
Answer» Right option is (c) 0.38 The BEST I can explain: The reflection coefficient in TERMS of intrinsic impedances is GIVEN by R = η2 – η1/η2 + η1. On substituting for η1 = 4 and η2 = 9, we get R = 9 – 4/9 + 4 = 5/13 = 0.38.

Discussion

86.	The characteristic impedance of a transmission line is normally chosen to be(a) 50(b) 75(c) 50 or 75(d) 100This question was addressed to me in homework.My question is from Input and Characteristic Impedances topic in portion Transmission Lines of Electromagnetic Theory
Answer» Right answer is (c) 50 or 75 Easiest explanation: The characteristic impedance is ALWAYS 50 OHM or 75 ohm for a TRANSMISSION LINE. This is because of the GHz range of OPERATION and the load impedences employed.

Discussion

87.	The minimum impedance of a transmission line 75 ohm with a standing wave ratio of 4 is(a) 75(b) 300(c) 18.75(d) 150This question was addressed to me during an interview for a job.Enquiry is from Input and Characteristic Impedances topic in chapter Transmission Lines of Electromagnetic Theory
Answer» RIGHT choice is (c) 18.75 For explanation: The minimum impedance of a line is GIVEN by Zmin = ZO/S. On substituting for Zo = 75 and S = 4, we get Zmin = 75/4 = 18.75 units.

Discussion

88.	The average power in an electromagnetic wave is given by(a) propagation constant(b) poynting vector(c) phase constant(d) attenuation constantThe question was asked in exam.Asked question is from Input and Characteristic Impedances topic in portion Transmission Lines of Electromagnetic Theory
Answer» CORRECT answer is (b) poynting VECTOR To explain I would say: The Poynting vector is the CROSS product of the electric field and magnetic field INTENSITIES. It gives the total power of an electromagnetic wave.

Discussion

89.	The maximum impedance of a transmission line 50 ohm and the standing wave ratio of 2.5 is(a) 20(b) 125(c) 200(d) 75I got this question in homework.This key question is from Input and Characteristic Impedances in section Transmission Lines of Electromagnetic Theory
Answer» Right option is (b) 125 The explanation is: The MAXIMUM impedance of a line is GIVEN by Zmax = SZO. On substituting for S = 2.5 and Zo = 50, we get Zmax = 2.5 X 50 = 125 ohm.

Discussion

90.	The group delay of the wave with phase constant of 62.5 units and frequency of 4.5 radian/sec is(a) 13.88(b) 31.88(c) 88.13(d) 88.31This question was addressed to me by my school principal while I was bunking the class.This interesting question is from Input and Characteristic Impedances in portion Transmission Lines of Electromagnetic Theory
Answer» Correct CHOICE is (a) 13.88 The best I can EXPLAIN: The GROUP delay is given by TD = β/ω. Given that β = 62.5 and ω = 4.5, we get the group delay as td = 62.5/4.5 = 13.88 units.

Discussion

91.	When the ratio of load voltage to input voltage is 5, the ratio of the characteristic impedance to the input impedance is(a) 1/5(b) 5(c) 10(d) 25The question was asked in semester exam.Question is taken from Input and Characteristic Impedances in division Transmission Lines of Electromagnetic Theory
Answer» Right CHOICE is (b) 5 For explanation I would say: From the transmission line equation, the ratio of the LOAD voltage to the input voltage is same as the ratio of the CHARACTERISTIC IMPEDANCE to the input impedance. Thus the required ratio is 5.

Discussion

92.	The power of the transmitter with a radiation resistance of 12 ohm and an antenna current of 3.5A is(a) 147(b) 741(c) 174(d) 471I have been asked this question in homework.This interesting question is from Input and Characteristic Impedances in chapter Transmission Lines of Electromagnetic Theory
Answer» CORRECT choice is (a) 147 The explanation is: The POWER in a transmitter is given by Prad = Iant^2 Rrad. On substituting Irad = 3.5 and Rrad =12, we get Prad = 3.5^2 x 12 = 147 UNITS.

Discussion

93.	The reflection coefficient lies in the range of(a) 0 < τ < 1(b) -1 < τ < 1(c) 1 < τ < ∞(d) 0 < τ < ∞The question was asked by my college professor while I was bunking the class.My doubt stems from Input and Characteristic Impedances topic in division Transmission Lines of Electromagnetic Theory
Answer» The correct option is (a) 0 < τ < 1 Easiest EXPLANATION: The reflection coefficient lies in the range of 0 < τ < 1. For FULL TRANSMISSION, the reflection will be zero. For no transmission, the reflection will be UNITY.

Discussion

94.	For a matched line, the input impedance will be equal to(a) Load impedance(b) Characteristic impedance(c) Output impedance(d) ZeroThe question was asked in unit test.This interesting question is from Input and Characteristic Impedances in chapter Transmission Lines of Electromagnetic Theory
Answer» RIGHT choice is (b) Characteristic impedance The BEST explanation: A matched LINE refers to the input and characteristic impedance being the same. In such CONDITION, maximum transmission will occur with MINIMAL losses. The reflection will be very low.

Discussion

95.	The input impedance of a quarter wave line 50 ohm and load impedance of 20 ohm is(a) 50(b) 20(c) 1000(d) 125The question was asked during an online exam.This is a very interesting question from Input and Characteristic Impedances in portion Transmission Lines of Electromagnetic Theory
Answer» RIGHT option is (d) 125 Easiest EXPLANATION: The characteristic impedance will be the geometric MEAN of the INPUT impedance and the load impedance. Thus Zo^2 = Zin ZL. On substituting for Zo = 50 and ZL = 20, we get the input impedance as 50^2/20 = 125 ohm.

Discussion

96.	The characteristic impedance of a quarter wave transformer with load and input impedances given by 30 and 75 respectively is(a) 47.43(b) 37.34(c) 73.23(d) 67.45I have been asked this question by my school teacher while I was bunking the class.My question is based upon Input and Characteristic Impedances topic in chapter Transmission Lines of Electromagnetic Theory
Answer» Correct OPTION is (a) 47.43 To elaborate: In quarter WAVE transformer, the characteristic impedance will be the GEOMETRIC mean of the input impedance and the load impedance. THUS Zo^2 = ZIN ZL. On substituting for ZIN = 75 and ZL = 30, we get the characteristic impedance as 47.43 UNITS.

Discussion

97.	The quarter wave transformer can be considered as a(a) Impedance inverter(b) Impedance doubler(c) Impedance tripler(d) Impedance quadruplerI have been asked this question in an internship interview.The question is from Transmission Line Equations in portion Transmission Lines of Electromagnetic Theory
Answer» The correct option is (a) Impedance inverter The best explanation: A quarter wave transformer MAY be CONSIDERED as an impedance inverter as it can TRANSFORM a LOW impedance into a HIGH impedance and vice-versa.

Discussion

98.	The purpose of the transmission line equation is to(a) Find primary parameters(b) Find secondary parameters(c) Find the reflection cofficient(d) Impedance matchingI have been asked this question in an interview for job.This intriguing question comes from Transmission Line Equations in division Transmission Lines of Electromagnetic Theory
Answer» Right option is (d) Impedance matching Easiest EXPLANATION: The transmission LINE equation is USEFUL in finding the length of the line which gives maximum power transfer. THUS it is useful for impedance matching.

Discussion

99.	The reflection coefficient of a perfectly matched transmission line is(a) 1(b) -1(c) 0(d) ∞I had been asked this question in homework.The query is from Transmission Line Equations in section Transmission Lines of Electromagnetic Theory
Answer» Correct option is (C) 0 Easiest EXPLANATION: In a perfectly MATCHED LINE, maximum power transfer will occur. Losses will be minimal. This implies UNITY transmission coefficient and zero reflection coefficient.

Discussion

100.	Find the characteristic impedance of a quarter wave with input and load impedances given by 50 and 25 respectively.(a) 50(b) 25(c) 75(d) 35.35I have been asked this question in my homework.Asked question is from Transmission Line Equations topic in section Transmission Lines of Electromagnetic Theory
Answer» Right answer is (d) 35.35 To explain I would say: For a quarter line wave, the CHARACTERISTIC impedance is the geometric mean of input and load impedances. Thus Zo^2 = Zin ZL. On substituting for Zin = 50 and ZL = 25, we get Zo^2 = 50 X 25. The characteristic impedance will be 35.35 OHM.

Discussion

Explore topic-wise InterviewSolutions in .

The skin depth is used to find which parameter?(a) DC resistance(b) AC resistance(c) Permittivity(d) PotentialThis question was posed to me by my school principal while I was bunking the class.My doubt is from Skin Effect topic in chapter Transmission Lines of Electromagnetic Theory

The skin effect is a phenomenon observed in(a) Insulators(b) Dielectrics(c) Conductors(d) SemiconductorsThe question was asked in an international level competition.My question comes from Skin Effect in section Transmission Lines of Electromagnetic Theory

The intrinsic impedance in free space is(a) 60π(b) 12π(c) 6π(d) 120πI have been asked this question in examination.My question is from Intrinsic Impedance and Propagation Constant in portion Transmission Lines of Electromagnetic Theory

The intrinsic angle is 25^0, find the loss angle.(a) 12.5(b) 50(c) 25(d) 75This question was posed to me at a job interview.This key question is from Intrinsic Impedance and Propagation Constant topic in chapter Transmission Lines of Electromagnetic Theory

The intrinsic impedance of a wave with electric and magnetic field of 10 and 8 respectively is(a) 1.6(b) 1.11(c) 1.25(d) 0.8The question was asked in homework.The question is from Intrinsic Impedance and Propagation Constant topic in division Transmission Lines of Electromagnetic Theory

The standing wave ratio ofshort circuited and open circuited lines will be(a) 0(b) 1(c) -1(d) ∞I have been asked this question in my homework.The above asked question is from Standing Waves and SWR in division Transmission Lines of Electromagnetic Theory

The minimum impedance of a 75 ohm transmission line with a SWR of 2.5 is(a) 100(b) 50(c) 25(d) 30I had been asked this question by my school teacher while I was bunking the class.Query is from Standing Waves and SWR topic in section Transmission Lines of Electromagnetic Theory

The maximum impedance of a 50 ohm transmission line with SWR of 3 is(a) 50/3(b) 3/50(c) 150(d) 450The question was asked in final exam.This interesting question is from Standing Waves and SWR in section Transmission Lines of Electromagnetic Theory

For matched line, the standing wave ratio will be(a) 0(b) ∞(c) -1(d) 1I had been asked this question in examination.My question comes from Standing Waves and SWR topic in division Transmission Lines of Electromagnetic Theory

The range of the standing wave ratio is(a) 0 < S < 1(b) -1 < S < 1(c) 1 < S < ∞(d) 0 < S < ∞This question was posed to me in exam.The query is from Standing Waves and SWR in portion Transmission Lines of Electromagnetic Theory

Find the reflection coefficient of the wave with SWR of 3.5.(a) 0.55(b) 0.23(c) 0.48(d) 0.68This question was posed to me during an interview.Enquiry is from Standing Waves and SWR in section Transmission Lines of Electromagnetic Theory

Find the standing wave ratio, when a load impedance of 250 ohm is connected to a 75 ohm line.(a) 0.3(b) 75(c) 250(d) 3.33I have been asked this question in class test.This interesting question is from Standing Waves and SWR topic in chapter Transmission Lines of Electromagnetic Theory

Given that the reflection coefficient is 0.6. Find the SWR.(a) 2(b) 4(c) 6(d) 8I have been asked this question during an interview for a job.Query is from Standing Waves and SWR in division Transmission Lines of Electromagnetic Theory

Standing waves occurs due to(a) Impedance match(b) Impedance mismatch(c) Reflection(d) TransmissionI have been asked this question by my college director while I was bunking the class.Asked question is from Standing Waves and SWR in section Transmission Lines of Electromagnetic Theory

In matched line, the transmission coefficient is(a) 0(b) 1(c) -1(d) InfinityThe question was asked by my college professor while I was bunking the class.My question is based upon Reflection and Transmission Coefficients in division Transmission Lines of Electromagnetic Theory

The transmission coefficient in a wave travelling through two media having permittivities 4 and 1 is(a) 1/4(b) 3/2(c) 3/4(d) 2/3I got this question during an online interview.Origin of the question is Reflection and Transmission Coefficients in chapter Transmission Lines of Electromagnetic Theory

The reflection coefficient of a wave with transmission coefficient 0.35 is(a) 1.35(b) 0.65(c) 0.35(d) 0.7This question was posed to me during an online interview.The query is from Reflection and Transmission Coefficients in division Transmission Lines of Electromagnetic Theory

The characteristic impedance of a transmission line is normally chosen to be(a) 50(b) 75(c) 50 or 75(d) 100This question was addressed to me in homework.My question is from Input and Characteristic Impedances topic in portion Transmission Lines of Electromagnetic Theory

The minimum impedance of a transmission line 75 ohm with a standing wave ratio of 4 is(a) 75(b) 300(c) 18.75(d) 150This question was addressed to me during an interview for a job.Enquiry is from Input and Characteristic Impedances topic in chapter Transmission Lines of Electromagnetic Theory

The average power in an electromagnetic wave is given by(a) propagation constant(b) poynting vector(c) phase constant(d) attenuation constantThe question was asked in exam.Asked question is from Input and Characteristic Impedances topic in portion Transmission Lines of Electromagnetic Theory

The maximum impedance of a transmission line 50 ohm and the standing wave ratio of 2.5 is(a) 20(b) 125(c) 200(d) 75I got this question in homework.This key question is from Input and Characteristic Impedances in section Transmission Lines of Electromagnetic Theory

The power of the transmitter with a radiation resistance of 12 ohm and an antenna current of 3.5A is(a) 147(b) 741(c) 174(d) 471I have been asked this question in homework.This interesting question is from Input and Characteristic Impedances in chapter Transmission Lines of Electromagnetic Theory

For a matched line, the input impedance will be equal to(a) Load impedance(b) Characteristic impedance(c) Output impedance(d) ZeroThe question was asked in unit test.This interesting question is from Input and Characteristic Impedances in chapter Transmission Lines of Electromagnetic Theory

The input impedance of a quarter wave line 50 ohm and load impedance of 20 ohm is(a) 50(b) 20(c) 1000(d) 125The question was asked during an online exam.This is a very interesting question from Input and Characteristic Impedances in portion Transmission Lines of Electromagnetic Theory

The reflection coefficient of a perfectly matched transmission line is(a) 1(b) -1(c) 0(d) ∞I had been asked this question in homework.The query is from Transmission Line Equations in section Transmission Lines of Electromagnetic Theory