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This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Mention the limitations of LC oscillators. |
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Answer» The value of resistors and inductors change due to changes in temperature. Hence, the frequency of LC and RC oscillator do not remain constant. |
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| 2. |
Mention any two applications of Colpitts oscillator. |
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Answer» Collpitts oscillator is used in: (i) Radio and TV transmitters (ii) Radio and TV receivers. |
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| 3. |
Write the expression for the voltage gain of a positive feedback amplifier. |
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Answer» Voltage gain with positive feedback, Af = \(\frac{A}{1-A\beta}\) |
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| 4. |
What is an oscillator? |
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Answer» Oscillator is a circuit that converts DC energy into an AC energy of desired frequency. |
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| 5. |
Write any two applications of Hartley oscillator. |
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Answer» Hartley oscillator is used in (i) Radio and TV transmitters. (ii) Radio and TV receivers. |
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| 6. |
What are undamped oscillations? |
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Answer» Undamped oscillations are electrical oscillations whose amplitude remains constant with respect to time. |
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| 7. |
How many RC branches are required for a phase shift oscillator? |
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Answer» Three RC branches are required for a phase shift oscillator. |
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| 8. |
Explain the conditions of Barkhaussan criterion. |
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Answer» (i) The total phase shift around the closed loop should be 0° or 360°. (ii) The magnitude of product of the open loop gain of the amplifier (A) and feedback ratio (P) is unity. i.e, |Aβ| = 1. |
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| 9. |
What is the type of feedback used in Colpitts oscillator? |
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Answer» Capacitive feedback. |
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| 10. |
Mention the principle used in crystal oscillator. |
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Answer» Piezo-electric effect. |
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| 11. |
Write the expression for the feedback factor of colpitts oscillator. |
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Answer» Feedback factor, \(\beta=\frac{C_1}{C_2}\) |
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| 12. |
Does the bridge circuit produce any phase shift in a Wein bridge oscillator? |
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Answer» No. The bridge circuit does not produce any phase shift. |
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| 13. |
Write the expression for feedback factor of wein bridge oscillator. |
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Answer» Feedback factor, \(\beta=\frac{1}{3}\) |
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| 14. |
Write the expression for the feedback factor of phase shift oscillator. |
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Answer» Feedback factor, \(\beta=\frac{R_i}{R_f}=\frac{1}{29}\) |
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| 15. |
What should be the value of capacitor required for a phase shift oscillator to produce a frequency of 338 Hz, if the resistance used is 220Ω. |
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Answer» f = 338 Hz R = 220Ω f = \(\frac{0.065}{RC}\) C = \(\frac{0.065}{Rf}\) = \(\frac{0.065}{220\times 338}\) = 0.874μF |
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| 16. |
What is the amount of phase shift in each RC section of a phase shift oscillator? |
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Answer» The amount of phase shift in each RC section of a phase shift oscillator is 60°. |
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| 17. |
What are damped oscillations? |
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Answer» Damped oscillations are electrical oscillations whose amplitude keeps on decreasing with time but frequency remains a constant. |
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| 18. |
RC Phase shift oscillator uses three identical RC sections in the feedback network. The values of the components are R = 680Ω and C = 220 nF. Determine the frequency of oscillation. |
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Answer» f = \(\frac{0.065}{RC}\) = \(\frac{0.065}{980\times 220\times 10^{-9}}\) = \(\frac{0.065}{680\times 220}\times 10^9\) = 434.4 Hz |
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| 19. |
What are sinusoidal oscillators? |
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Answer» Oscillators that produce sinusoidal waveforms are called sinusoidal oscillators. |
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| 20. |
What are non-sinusoidal or relaxation oscillators? |
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Answer» Oscillators that produce non-sinusoidal waves like triangular wave, square wave or sawtooth waves are called non-sinusoidal oscillators. |
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| 21. |
Mention any two advantages of a crystal oscillator over LC and RC oscillators. |
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Answer» (i) They have high frequency stability. (ii) They are used as a reference for measurement and comparison of frequencies. |
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| 22. |
Write any two advantage of RC oscillators over LC oscillators. |
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Answer» (i) RC oscillators provide constant output and good stability. (ii) RC oscillators do not require any inductor and hence size and cost get reduced. |
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| 23. |
Write the expression for the frequency of oscillation of a Hartley oscillator. |
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Answer» Frequency, \(f=\frac{1}{2\pi\sqrt{LC_s}}\) where L = L1 + L2 |
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