# MCQs on Filters and Attenuators

## MCQs on Filters and Attenuators

MCQs on Filters and Attenuators, Objective Questions on Filters and Attenuators, MCQs on Filters, MCQs on Attenuators, Filters MCQ, Attenuators MCQ, Gate Questions on Filters, Gate Questions on Attenuators

### Objective Type Questions

1. A 26 dB output in watts is equal to
• 2.4 w
• 0.26 w
• 0.156 w
• 0.4 w

2. The characteristic impedance of an LPF in attenuation band is

• Purely imaginary
• Zero
• Complex frequency
• Real value

3. The real part of the propagation constant shows:

• Variation of voltage and current on basic unit
• Variation of phase shift/position of voltage
• Reduction in voltage, current value of signal amplitude.
• Reduction of only voltage amplitude.

Answer: Reduction in voltage, current value of signal amplitude.

4. The purpose of an attenuator is to

• Increase signal strength
• Decrease reflections
• Decrease value of signal strength
• Provide impedance matching

Answer: Decrease value of signal strength

5. In a transmission line terminated by characteristic impedance, Z0

• There is no reflection of the incident wave
• The reflection is maximum due to termination.
• There are a large number of maximum and minimum on the line.
• The incident current is zero for any applied signal.

Answer: There is no reflection of the incident wave

6. An attenuator is a

• Resistive network
• R-L network
• R-C network
• L-C network.

7. If ‘α’ attenuation in nepers, then

• Attenuation in $dB=\frac{\alpha }{0.8686}$
• Attenuation in dB = 8.686α
• Attenuation in dB = 0.1α
• Attenuation is dB = 0.01α

Answer: Attenuation in dB = 8.686α

8. For a constant K-type high-pass π-Section filter, characteristic impedance Z0 for f < fc is

• Resistance
• Inductive
• Capacitive
• Inductive or capacitive

9. An ideal filter should have

• Zero attenuation in the pass band
• Zero attenuation in the attenuation band
• Infinite attenuation in the pass band
• Infinite attenuation in the attenuation band.

Answer: Zero attenuation in the pass band

10. For an m-derived HPF, the cut-off frequency is 4 kHz and the filter has an infinite attenuation at 3.6 kHz, the value of m is

• 0.436
• 4.36
• 0.34
• 0.6

11. If ZOC = 120 Ω and ZSC = 30 Ω, the characteristic impedance is

• 30 Ω
• 60 Ω
• 120 Ω
• 150 Ω

12. If ZOC = 100 Ω and ZSC = 64 Ω, the characteristic impedance is

• 400 Ω
• 60 Ω
• 80 Ω
• 170 Ω

13. The frequency of infinite attenuation (f) of a low-pass m-derived section is

• Equal to fc
• f = ∞
• Close to but greater than fc
• Close to but less than fc of the filter

Answer: Close to but greater than fc

14. A constant K-type BPF has pass band from 1000 Hz to 4000 Hz. The resonance frequency of shunt and series arm is a

• 2500 Hz
• 500 Hz
• 2000 Hz
• 3000 Hz

15. A constant K-type low-pass T-section filter has Z0 = 600 Ω at zero frequency. At f=fc, the characteristic impedance is

• 600 Ω
• 0 Ω
• ∞ Ω
• more than 600 Ω

16. In m-derived terminating half section, m is equal to

• 0.1
• 0.3
• 0.6
• 0.9

17. In a symmetrical T-type attenuator with attenuation N and characteristic impedance R0, the resistance of each series arm is equal to

• R0
• (N − 1) R0
• $\frac{2N}{N^{2}-1}R_{0}$
• $\frac{N}{N^{2}-1}R_{0}$

Answer: $\frac{2N}{N^{2}-1}R_{0}$

18. For a transmission line, open-circuit and short-circuit impedance are 20Ω and 5 Ω. The characteristic impedance of the line is

• 10 Ω
• 20 Ω
• 25 Ω
• 100 Ω

19. For a prototype LPF, the phase constant β in the attenuation band is

• α
• 0
• $\frac{\pi }{2}$

20. In the m-derived HPF, the resonant frequency is to be chosen so that it is

• Above the cut-off frequency
• Below the cut-off frequency
• Equal to the cut-off frequency
• Infinitely high

21. In a symmetrical π-section attenuator with attenuation N and characteristic impedance R0, the resistance of each shunt arm is equal to

• R0
• (N − 1) R0
• $\frac{N-1}{N+1}R_{0}$
• $\frac{N+1}{N-1}R_{0}$

Answer: $\frac{N+1}{N-1}R_{0}$

22. Bridged T-type network can be used as

• Attenuator
• LPF
• HPF
• BPF

23. One neper is equal to

• 0.8686 dB
• 8.686 dB
• 0.115 dB
• 86.86 dB

24. Terminating half sections used in composite filters are built with the following value of m

• 0.3
• 0.8
• 0.1
• 0.6

25. A transmission line works as

• Attenuator
• LPF
• HPF
• None of these