Transmission Line Theory MCQs

1. What is the primary characteristic of a transmission line?
A) Low impedance
B) High resistance
C) Wave propagation
D) DC conduction
Answer: C) Wave propagation

2. What is the characteristic impedance of a transmission line?
A) Depends on the voltage
B) Depends on the current
C) Depends on the frequency
D) Intrinsic property of the line
Answer: D) Intrinsic property of the line

3. A transmission line with a characteristic impedance of 50 ohms operates at a frequency of 1 GHz. What is the wavelength of the signal on this line?
A) 15 cm
B) 30 cm
C) 20 cm
D) 10 cm
Answer: A) 15 cm

4. What happens to a signal when it reaches the end of a transmission line and is not terminated correctly?
A) Reflects back
B) Absorbed by the load
C) Continues without any change
D) Dissipated as heat
Answer: A) Reflects back

5. What is the purpose of matching the load impedance to the characteristic impedance of the transmission line?
A) To reduce power consumption
B) To minimize signal attenuation
C) To maximize signal reflection
D) To minimize interference
Answer: B) To minimize signal attenuation

6. In a transmission line, what is the effect of increasing the frequency of the signal?
A) Decreases the wavelength
B) Increases the characteristic impedance
C) Decreases the attenuation
D) Increases the line capacitance
Answer: A) Decreases the wavelength

7. What is the primary cause of signal loss in a transmission line?
A) Skin effect
B) Dielectric absorption
C) Resistive losses
D) Capacitive coupling
Answer: C) Resistive losses

8. In a coaxial transmission line, where is the electric field primarily located?
A) Between the inner and outer conductors
B) Inside the inner conductor
C) Outside the outer conductor
D) Throughout the dielectric material
Answer: A) Between the inner and outer conductors

9. What is the purpose of using a twisted pair in transmission lines?
A) Increase signal speed
B) Reduce electromagnetic interference
C) Increase characteristic impedance
D) Reduce attenuation
Answer: B) Reduce electromagnetic interference

10. What is the effect of increasing the length of a transmission line on signal integrity?
A) Decreases signal delay
B) Increases signal attenuation
C) Decreases characteristic impedance
D) Increases voltage level
Answer: B) Increases signal attenuation

11. What parameter of a transmission line is determined by its physical dimensions and material properties?
A) Bandwidth
B) Attenuation
C) Characteristic impedance
D) Frequency response
Answer: C) Characteristic impedance

12. What type of transmission line consists of a single conductor surrounded by a dielectric material?
A) Coaxial cable
B) Twisted pair
C) Waveguide
D) Microstrip line
Answer: D) Microstrip line

13. Which type of transmission line is suitable for high-frequency applications due to its low loss and low electromagnetic interference?
A) Coaxial cable
B) Twisted pair
C) Open-wire line
D) Waveguide
Answer: A) Coaxial cable

14. What is the consequence of mismatched impedance between a source, transmission line, and load?
A) Decreased signal power
B) Increased signal speed
C) Reduced signal reflection
D) Increased signal attenuation
Answer: D) Increased signal attenuation

15. What determines the maximum power handling capacity of a transmission line?
A) Wavelength
B) Frequency
C) Line voltage
D) Peak voltage rating
Answer: D) Peak voltage rating

16. What is the primary function of a balun in a transmission line system?
A) Match impedances
B) Convert unbalanced to balanced signals
C) Reduce signal distortion
D) Increase signal speed
Answer: B) Convert unbalanced to balanced signals

17. What is the effect of increasing the operating frequency on the skin effect in a transmission line?
A) Decreases skin depth
B) Increases conductor resistance
C) Decreases signal reflection
D) Increases signal speed
Answer: A) Decreases skin depth

18. What is the typical characteristic impedance of a coaxial cable used in many communication systems?
A) 75 ohms
B) 50 ohms
C) 100 ohms
D) 300 ohms
Answer: B) 50 ohms

19. What is the primary reason for using transmission lines in high-frequency applications instead of direct connections?
A) Reduce power consumption
B) Minimize signal attenuation
C) Maximize signal reflection
D) Increase signal delay
Answer: B) Minimize signal attenuation

20. Which type of transmission line is used in radio frequency (RF) applications where low loss and high power handling are critical?
A) Microstrip line
B) Waveguide
C) Coaxial cable
D) Twin lead line
Answer: C) Coaxial cable

21. In transmission line theory, what is the consequence of having a standing wave ratio (SWR) greater than 1?
A) Maximum power transfer
B) Minimum signal attenuation
C) Signal reflection
D) Maximum signal delay
Answer: C) Signal reflection

22. What property of a transmission line determines the velocity of propagation of signals?
A) Dielectric constant of the material
B) Conductor resistance
C) Frequency of the signal
D) Line length
Answer: A) Dielectric constant of the material

23. What type of transmission line is used in low-frequency applications due to its simplicity and low cost?
A) Coaxial cable
B) Microstrip line
C) Twin lead line
D) Waveguide
Answer: C) Twin lead line

24. What effect does increasing the conductor diameter have on the characteristic impedance of a transmission line?
A) Increases impedance
B) Decreases impedance
C) No effect on impedance
D) Increases signal speed
Answer: B) Decreases impedance

25. What happens to the velocity of propagation in a transmission line when the dielectric constant of the material increases?
A) Increases
B) Decreases
C) Remains constant
D) Depends on the frequency
Answer: B) Decreases

26. What is the primary advantage of using a waveguide over other transmission lines?
A) Higher power handling
B) Lower attenuation
C) Easier installation
D) Higher characteristic impedance
Answer: A) Higher power handling

27. What is the function of a stub in a transmission line system?
A) Match impedances
B) Reduce signal attenuation
C) Increase signal reflection
D) Convert AC to DC
Answer: A) Match impedances

28. What is the purpose of a transmission line transformer?
A) Match impedances
B) Increase signal power
C) Decrease signal speed
D) Reduce signal reflection
Answer: A) Match impedances

29. What is the main drawback of using open-wire transmission lines?
A) High attenuation
B) Susceptible to interference
C) High cost
D) Limited bandwidth
Answer: B) Susceptible to interference

30. Which parameter of a transmission line increases with increasing frequency?
A) Attenuation
B) Characteristic impedance
C) Capacitance per unit length
D) Inductance per unit length
Answer: C) Capacitance per unit length

31. What type of transmission line is used in printed circuit boards for RF applications?
A) Coaxial cable
B) Waveguide
C) Microstrip line
D) Twin lead line
Answer: C) Microstrip line

32. What is the characteristic impedance of a transmission line that has a capacitance of 50 pF/m and an inductance of 0.2 µH/m?
A) 100 ohms
B) 50 ohms
C) 200 ohms
D) 75 ohms
Answer: A) 100 ohms

33. What happens to the velocity of propagation in a transmission line when the spacing between conductors decreases?
A) Increases
B) Decreases
C) Remains constant
D) Depends on the frequency
Answer: A) Increases

34. In transmission line theory, what is the primary purpose of a quarter-wave transformer?
A) Increase signal power
B) Decrease signal delay
C) Match impedances
D) Reduce signal reflection
Answer: C) Match impedances

35. What is the primary cause of distortion in signals transmitted through a transmission line?
A) Attenuation
B) Dispersion
C) Reflection
D) Crosstalk
Answer: B) Dispersion

36. Which type of transmission line is most suitable for broadband applications?
A) Coaxial cable
B) Microstrip line
C) Waveguide
D) Open-wire line
Answer: C) Waveguide

37. What is the effect of increasing the length of a transmission line beyond a certain point?
A) Decreases signal delay
B) Reduces signal reflection
C) Increases signal attenuation
D) Increases characteristic impedance
Answer: C) Increases signal attenuation

38. What is the primary reason for using transmission line theory in the design of high-frequency systems?
A) Reduce signal power
B) Minimize signal distortion
C) Increase signal reflection
D) Decrease signal delay
Answer: B) Minimize signal distortion

39. What is the function of the insulating material (dielectric) in a transmission line?
A) Increase current flow
B) Decrease signal speed
C) Increase signal reflection
D) Provide mechanical support
Answer: D) Provide mechanical support

40. Which type of transmission line is used in satellite communication systems for its ability to handle high power and low loss?
A) Coaxial cable
B) Waveguide
C) Microstrip line
D) Open-wire line
Answer: B) Waveguide

41. What is the typical value of velocity of propagation in coaxial cable transmission lines?
A) 2.5 × 10^8 m/s
B) 3.0 × 10^8 m/s
C) 2.0 × 10^8 m/s
D) 2.2 × 10^8 m/s
Answer: B) 3.0 × 10^8 m/s

42. What is the consequence of using transmission line theory to design antennas?
A) Increase in signal attenuation
B) Decrease in bandwidth
C) Improvement in radiation efficiency
D) Increase in standing wave ratio
Answer: C) Improvement in radiation efficiency

43. Which transmission line parameter determines the maximum voltage that can be safely applied without breakdown?
A) Characteristic impedance
B) Attenuation
C) Peak voltage rating
D) Frequency response
Answer: C) Peak voltage rating

44. What is the main reason for using twisted pair cables in telephone systems?
A) High bandwidth
B) Low cost
C) High power handling
D) Low electromagnetic interference
Answer: D) Low electromagnetic interference

45. What is the typical range of characteristic impedance for waveguide transmission lines used in microwave frequencies?
A) 50 to 75 ohms
B) 200 to 500 ohms
C) 25 to 40 ohms
D) 1000 to 5000 ohms
Answer: D) 1000 to 5000 ohms

46. Which transmission line type is least affected by external electromagnetic interference?
A) Twisted pair
B) Coaxial cable
C) Open-wire line
D) Microstrip line
Answer: B) Coaxial cable

47. What is the effect of increasing the operating frequency on the attenuation of signals in a transmission line?
A) Decreases attenuation
B) Increases attenuation
C) No effect on attenuation
D) Decreases signal speed
Answer: B) Increases attenuation

48. What happens to the characteristic impedance of a transmission line when the spacing between conductors increases?
A) Increases
B) Decreases
C) Remains constant
D) Depends on the frequency
Answer: B) Decreases

49. Which parameter of a transmission line decreases with increasing frequency?
A) Attenuation
B) Inductance per unit length
C) Capacitance per unit length
D) Characteristic impedance
Answer: D) Characteristic impedance

50. In transmission line theory, what is the function of a directional coupler?
A) Combine signals
B) Match impedances
C) Measure power
D) Amplify signals
Answer: C) Measure power

Transmission Line Theory MCQs

More MCQs on Electrical Engineering (Power) MCQs

Leave a Comment Cancel reply