Sine Wave Oscillator Principle MCQ [Free PDF] - Objective Question Answer for Sine Wave Oscillator Principle Quiz

21. The value of the feedback resistor in the phase shift oscillator is 180kΩ. Find its input resistance?

A. 52kΩ
B. 151kΩ
C. 209kΩ
D. 6.2kΩ

Answer: C

To obtain sustained oscillation in phase shift oscillator.

=> |A|=29 or |R_f / R₁|=29

=> R₁|= R_f / 29 = 180kΩ/29= 6.21kΩ,

22. Determine the frequency of oscillation (f_o) in phase shift oscillator?

A. f_o = √6/ωRC
B. f_o = 0.56/ωRC
C. f_o = 0.065/ωRC
D. f_o = 6/ωRC

Answer: C

The frequency of oscillation of phase shift oscillator is given as

f_o = 1/(2π×RC×√6) = 1/15.38×RC

=> f_o = 0.065/RC.

23. The condition for zero phase shift in wein bridge oscillator is achieved by

A. Connecting feedback to the non-inverting input terminal of op-amp
B. Balancing the bridge
C. Applying a parallel combination of RC to the feedback network
D. All of the mentioned

Answer: B

In wein bridge oscillator, the feedback signal in the circuit is connected to the non-inverting input of the op-amp. So, the feedback network does not provide any feedback and the condition of zero phase shift around the circuit is achieved by balancing the bridge.

24. What is the frequency of oscillation of wein bridge oscillator?

A. f_o = 1/(2πRC.
B. f_o = 2π/RC
C. f_o = RC/2π
D. f_o = 2πRC

Answer: A

The frequency of oscillation of wein bridge oscillator is f_o=2πRC.

25. Sustained oscillation in wein bridge oscillator is possible when the value of ß is

A. 3
B. 1/3
C. 1
D. None of the mentioned

Answer: B

The gain |A|≥3, for oscillation to keep growing ( Since, |Aß|≥1 for sustained oscillation).

26. Determine the value of f_o, ß and R_f from the following circuit diagram.

A. f_o = 80Hz, ß = 0.162 and R_f = 7kΩ
B. f_o = 100Hz, ß = 1.62 and R_f = 7kΩ
C. f_o = 60Hz, ß = 0.0162 and R_f = 7kΩ
D. f_o = 120Hz, ß = 16.2 and R_f = 7kΩ

Answer: C

The frequency of oscillation for the circuit is given as,

f_o = 1/(2π×√(R₁R₂C₁C₂))

= 1/(2π×√(2.7kΩ×5kΩ×0.1µF×6µF)

= 1/(2π×2.85×10^-3)

=> f_o = 55.8 = 60Hz.

The value of ß = (R₂C₁) / (R₁C₁ + R₂C₂ + R₂C₁)

= (5kΩ×0.1µF)/(2.7kΩ×0.1µF+5kΩ×6µF+5kΩ×0.1µF)= 0.0162.

R_f =2 R₃

=> R_f = 2×3.5kΩ=7kΩ.

27. What is the problem faced by the wein bridge oscillator?

A. Output sinewave gets clipped
B. Output sinewave remains constant without growing
C. Output sinewave keep on decreasing and die out
D. All of the mentioned

Answer: A

The gain of wein bridge oscillator is greater than 3, sometimes this may keep the oscillations growing and it may clip the output sinewave.

28. Find the type of oscillator shown in the diagram

A. Quadrature oscillator
B. Biphasic oscillator
C. RC phase shift oscillator
D. None of the mentioned

Answer: D

The circuit shown is the practical wein bridge oscillator with adaptive negative feedback.

29. Calculate the value of capacitance in wein bridge oscillator, such that f_o =1755Hz and R=3.3kΩ.

A. 2.7µF
B. 0.91µF
C. 0.03µF
D. 0.05µF

Answer: C

The frequency of oscillation is given as f_o = 0.159/RC

=> C = 0.159/R×f_o

= 0.159/3.3kΩ×1755Hz

=> C = 0.027µF = 0.03µF.

30. Quadrature oscillators have signals with

A. Different frequency
B. Same frequency
C. Opposite frequency
D. Parallel frequency

Answer: B

In Quadrature oscillators, signals have the same frequency but have phase shifts respective to each other.

31. Which of the following component is not used for audio frequency?

A. RC oscillator
B. Wein bridge oscillator
C. LC oscillator
D. None of the mentioned

Answer: C

RC and wein bridge oscillators are suitable for audio frequency range because the size of R and C components becomes very large for generating low frequencies.

32. If the resistor and capacitor values are the same in the Quadrature oscillator. Find its frequency of oscillation for R=50kΩ and C=0.01µF.

A. 112Hz
B. 275Hz
C. 159Hz
D. 318Hz

Answer: D

Frequency of Quadrature oscillator, f_o = 1/(2πRC.

=> f_o= 1/(2π×50kΩ×0.01µF)= 318Hz.

33. What is the possible method used in a Quadrature oscillator to remove distortion from the output waveform?

A. Replace the resistor at the input of a non-inverting type amplifier with a potentiometer
B. Replace the resistor at the output of a non-inverting type amplifier with a potentiometer
C. Replace the resistor at the input of inverting type amplifier with a potentiometer
D. None of the mentioned

Answer: A

The resistor at the input of a non-inverting type amplifier is replaced with a potentiometer to eliminate any possible distortion in the output waveform.

34. A Biphasic oscillator produces an output signal that has

A. Cosine wave only
B. Both sine and cosine wave
C. Two identical sine wave
D. Two identical cosine wave

Answer: C

A biphasic oscillator is a sine wave oscillator. Therefore, the output signals will be two identical sine waves that are 180^o out of phase with each other.

35. If the output of the sinewave oscillator is Vsinω_ot, then determine the output of the inverter in the Biphasic oscillator.

A. Vsin(ω_ot+(3π/2))
B. Vsin(ω_ot+2π)
C. Vsin(ω_ot+π)
D. Vsin(ω_ot+(π/2))

Answer: B

Since the output of the Biphasic oscillator is 180^o out of phase with each other. The sine wave passing through the inverting amplifier (with a gain of one) outputs the signal with a 180^o phase shift.

36. A function generator can produce

A. Many identical waves
B. Square and sine waves only
C. Different types of waves simultaneously
D. None of the mentioned

Answer: Oscillator circuits generate only one type of waveform like square, triangular, or sine wave separately, whereas a function generator can produce all three types of waves simultaneously. [/bg_collapse]

37. Which of the following have distorted sinewave?

A. Function generator
B. Biphasic oscillator
C. RC phase shift oscillator
D. Wein bridge oscillator

Answer: A

The sine shaper in the function generator produces a sine wave by rounding off the tips of the triangular wave. The distortion of the sine wave thus produced is very high compared to the sine waves generated by another oscillator.

38. Usually circuit producing sine waves are called as

A. Oscillators
B. Generators
C. Multivibrators
D. All of the mentioned

Answer: A

The generators and the oscillators are equivalent terms, they can be interchangeable. Therefore, the circuits producing sine waves are called oscillators, while those generating a square wave or triangular wave are generators.

39. An IC function generator can allow the signals for

A. Amplitude Modulation (AM)
B. Frequency Modulation (FM)
C. Frequency Shift Keying (FSK)
D. All of the mentioned

Answer: D

IC function generator allows FM, AM, and FSK of signals in addition to producing different waveforms with variable duty cycle pulse.

40. The current in the XR-2206 Function generator is determined by

A. External resistors
B. External capacitors
C. External capacitors or external resistors
D. Both external capacitor and external resistor

Answer: C

The constant current is determined by the external resistors connected to current switches or the external capacitor connected to the current-controlled oscillator.

41. What will be the output, if a 180Ω resistor that was connected between the 13th and 14th pin terminal is removed.

A. A triangular wave
B. A sine wave
C. A square wave
D. A rectangular wave

Answer: A

When pins 13 and 14 are open, the gain of the sine shaper becomes linear and the output from the sine shaper will be a triangular wave.

42. Find the difference of potential that can be applied to the XR-2206 function generator.

A. 26v
B. 5v
C. 19v
D. 30v

Answer: C

If the power is applied to both V⁺ and V^– inputs. Then, the difference of potential (i.e. V⁺ – V^–) should be at least +10v but less than 26v.

43. The value of current and frequency of the output waveform is 5A and 13.33kHz. Find the capacitance value in the function generator?

A. 250µF
B. 120µF
C. 850µF
D. 370µF

Answer: B

The frequency of the output waveform f=(0.32×I)/C

=> C=(0.32×I)/f

= (0.32×5A./13.33kHz = 120µF.

44. How many sets of pins are required to control the frequency in the XR-2206 function generator?

A. Two
B. Three
C. Four
D. None of the mentioned

Answer: B

Frequency can be controlled by three sets of pin

1) Capacitor (100pF≤C≤100µF) connected to the current controlled oscillator
2) Resistor connected between the current switches
3) Voltage at Frequency Shift Keying connected to current switches.

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