Electronic Engineering MCQ Question Papers: ENTC, IT Interview Placement

Subject: Electromagnetic and Transmission Lines 6

**Part 6: List for questions and answers of Electro Magnetics & Transmission Line**

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**Q1. A material has conductivity of 10-2 mho/m and a relative permittivity of 4. The ****frequency at which conduction current in the medium is equal to displacement current is**

**a) 45 MHz**

**b) 90 MHz**

**c) 450 MHz**

**d) 900 MHz**

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**Q2. A transmission line is feeding 1 watt of power to a horn antenna having a gain of 10 dB. ****The antenna is matched to the transmission line. The total power radiated by the horn ****antenna into the free space is**

**a) 10 watt**

**b) 1 watt**

**c) 0.1 watt**

**d) 0.01 watt**

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**Q3. An end fire array consisting of several half-wave lengths of directive gain 40, then find ****the width of major lobe**

**a) 60**

**b) 50**

**c) 51.25**

**d) None of the above**

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**Q4. A uniform plane EM wave incident normally on a plane surface of a dielectric material is ****reflected with a VSWR of 3. What percentage of incident power that is reflected?**

**a) 10%**

**b) 25%**

**c) 50%**

**d) 75%**

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**Q5. Poynting vector is associated with which of the following?**

**a) Power flow in electromagnetic**

**b) Flux in magnetic field**

**c) Charge in electrostatic field**

**d) Current in electrostatic field **

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**Q6. A broadside array consisting of 200 cm wavelength with 10 half-wave dipole spacing 10 ****cm. And if each array element feeding with 1 amp. current and operating at same frequency ****then find the radiated power**

**a) 730 W**

**b) 73 W**

**c) 100 W**

**d) None**

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**Q7. If wave of critical frequency 30 MHz is departing at an angle of 60° , then the MUF is ****given to be**

**a) 10 MHz**

**b) 15 MHz**

**c) 30 MHz**

**d) 60 MHz**

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**Q8. An antenna having an effective temperature of 27°K is fed into a microwave amplifier ****that has an effective noise temperature of 30 K. Calculate the available noise power per unit ****bandwidth**

**a) 30 K**

**b) 57 K**

**c) 27 K**

**d) 3K, K is Boltzmann constant**

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**Q9. A 10 GHz signal propagates in a waveguide with a phase velocity of 4 x 10^8 m/s. If the ****signal produces standing wave in the guide, then the distance between successive minimal ****will be**

**a) 10 mm**

**b) 20 mm**

**c) 30 mm**

**d) 40 mm**

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**Q10. A transmission line has characteristics impedance of (75 + j 0.01) ohm and is terminated ****in a load impedance of (70 + j 50) ohm. The transmission coefficient will be**

**a) 1.70 – j 2.97**

**b) 0.08 + j 0.32**

**c) 1.32 + j 1.38**

**d) 1.08 + j 0.32 **

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**Q11. Maximum effective aperture of an antenna which is operating at a wavelength of 3 ****meters and has a directivity of 100**

**a) 71.68 m^2**

**b) 716 m^2**

**c) 7.16 m^2**

**d) 71.6 m^2**

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**Q12. The distance between maxima and minima of a standing wave is**

**a) **λ **/4**

**b) **λ **/2**

**c) **λ

**d) 2**** λ **

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**Q13. A TV. transmitting aerial is fixed on top of a 150 metre tower located on a mountain ****1200 m height. The range of transmitter is**

**a) 51 km**

**b) 152 km**

**c) 152 m**

**d) 51 m**

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**Q14. A vertical wire of 1 meter length carries a current of 1 A at 10 MHz. The total radiated ****power is nearly**

**a) 0.13 W**

**b) 0.88 W**

**c) 7.3 W**

**d) 73 W**

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**Q15. The length of half-wave antenna is at 30 MHz**

**a) 2.5 meter**

**b) 5 meter**

**c) 10 meter**

**d) 100 meter**

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**Q16. For a 400 kHz transmission line having L = 0.5 mH/km, C = 0.08 mF and negligible R and ****G, the characteristic impedance will be**

**a) 14 ohm**

**b) 28 ohm**

**c) 39 ohm**

**d) 79 ohm**

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**Q17. Which one of the following statement is not a correct for a plane wave with = 0.5e^-0.1x ****cos (10^6t – 2x)az A/m?**

**a) The wave frequency is 10^-6 r.p.s.**

**b) The wavelength is 3.14 m**

**c) The wave travels + x direction**

**d) Wave is polarized in the z direction**

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**Q18. The length of half-wave antenna is at 30 MHz**

**a) 2.5 meter**

**b) 5 meter**

**c) 10 meter**

**d) 100 meter**

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**Q19. Beamwidth (between first nulls) will be for an antenna at 3 MHz with directivity of 100**

**a) 140°**

**b) 70°**

**c) 210°**

**d) 60°**

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**Q20. Calculate the wave number in waveguide having dimensions 4 x 2 cm at 3 GHz**

**a) 6.28**

**b) 62.8**

**c) 8**

**d) 0 **

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**Part 6: List for questions and answers of Electroma**
**gnetic**
** & Transmission Line**

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**Q1. Answer: a**

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**Q2. Answer: a**

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**Q3. Answer: c**

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**Q4. Answer: b**

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**Q5. Answer: a**

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**Q6. Answer: a**

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**Q7. Answer: d**

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**Q8. Answer: b**

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**Q9. Answer: b**

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**Q10. Answer: d**

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**Q11. Answer: d**

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**Q12. Answer: a**

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**Q13. Answer: b**

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**Q14. Answer: d**

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**Q15. Answer: b**

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**Q16. Answer: d**

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**Q17. Answer: d**

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**Q18. Answer: b**

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**Q19. Answer: a**

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**Q20. Answer: b**