# Electronic Devices and Circuits Questions and Answers – Frequency Response – 1

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Frequency Response – 1”.

1. A parallel resonant circuit has a resistance of 2k ohm and half power frequencies of 86 kHz and 90 kHz. What is the value of capacitor?
a) 6 µF
b) 20 nF
c) 2 nF
d) 60 µF

Explanation: BW = 2p(90-86)k = 1/RC or C = 19.89 nF.

2. A parallel resonant circuit has a resistance of 2k ohm and half power frequencies of 86 kHz and 90 kHz. What is the value of the inductor?
a) 4.3 mH
b) 43 mH
c) 0.16 mH
d) 1.6 mH

Explanation: w = (86 + 90)k/2 = 88 = (1/LC)(0.5) or L = 0.16 mH.

3. A parallel resonant circuit has a resistance of 2k ohm and half power frequencies of 86 kHz and 90 kHz. What is the quality factor?
a) 22
b) 100
c) 48
d) 200

Explanation: Q = w/BW = 176pK/8pk = 22.

4. A parallel resonant circuit has a midband admittance of 25 X 10(-3) S, quality factor of 80 and a resonant frequency of 200 krad s. What is the value of R (in ohm)?
a) 40
b) 56.57
c) 80
d) 28.28

Explanation: At mid-band frequency Y = 1/R or R = 1000/25 or 40 ohm.

5. A parallel resonant circuit has a midband admittance of 25 X 10(-3) S, quality factor of 80 and a resonant frequency of 200 krad s. What is the value of C?
a) 2 µF
b) 28.1 µF
c) 10 µF
d) 14.14 µF

Explanation: Q = wRC or C = 80/(200 x 1000 x 40) or 10 µF.
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6. A parallel RLC circuit has R 1 k and C 1 F. The quality factor at resonance is 200. The value of inductor is
a) 35.4 H
b) 25 H
c) 17.7 H
d) 50 H

Explanation: Use Q = R (L/C)0.5.

7. A parallel circuit has R = 1k ohm , C = 50 µF and L = 10mH. The quality factor at resonance is
a) 100
b) 90.86
c) 70.7
d) None of the above

Explanation: Use Q = R (L/C)0.5.

8. A series resonant circuit has L = 1 mH and C = 10 F. The required R (in ohm) for the BW = 15 9 . Hz is
a) 0.1
b) 0.2
c) 0.0159
d) 500

Explanation: Use BW = R/L.

9. For the RLC parallel resonant circuit when R = 8k, L = 40 mH and C = 0.25 F, the quality factor
Q is
a) 40
b) 20
c) 30
d) 10

Explanation: use Q = R (C/L)0.5.

10. A series resonant circuit has an inductor L = 10 mH. The resonant frequency w = 10^6 rad/s and bandwidth is BW = 103 rad/s. The value of R and C will be
a) 100 F, 10 ohm
b) 100 pF, 10 ohm
c) 100 pF, 10 Mega-ohm
d) 100 µF, 10 Meg-ohm

Explanation: Use wxw = 1/LC and BW = R/L.

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