MCQOPTIONS
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MCQOPTIONS
This section includes 37 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Consider the followingI. OscillatorII. Emitter followerIII. Cascaded amplifierIV. Power amplifierWhich of the following use feedback amplifiers? |
| A. | I and II |
| B. | I and III |
| C. | II and IV |
| D. | III and IV |
| Answer» B. I and III | |
| 2. |
Magnetron is a |
| A. | High power microwave amplifier |
| B. | High power microwave oscillator |
| C. | Low power microwave amplifier |
| D. | Low power microwave oscillator |
| Answer» C. Low power microwave amplifier | |
| 3. |
Feedback is said to be positive if |
| A. | the feedback signal gets subtracted from the input signal |
| B. | the feedback signal gets added to the input signal |
| C. | any increase in the output signal results in a feedback signal which on being mixed with the input signal causes further increase in magnitude of the output signal |
| D. | none of these |
| Answer» D. none of these | |
| 4. |
An Op amp has Gain Bandwidth Product of 1 MHz. At what frequency will gain of this Op amp be equal to unity? Identify form the options given below. |
| A. | 100 kHz |
| B. | 1000 kHz |
| C. | 10 kHz |
| D. | 10 MHz |
| Answer» C. 10 kHz | |
| 5. |
Hartley Oscillator is a: |
| A. | Low frequency oscillator |
| B. | High frequency oscillator |
| C. | Stable frequency oscillator |
| D. | Relaxation frequency oscillator |
| Answer» C. Stable frequency oscillator | |
| 6. |
A circuit using op-amp shown below has |
| A. | Voltage series feedback |
| B. | Voltage shunt feedback |
| C. | Current shunt feedback |
| D. | Current series feedback |
| Answer» C. Current shunt feedback | |
| 7. |
Piezoelectric effect is carried out in |
| A. | Composite filter |
| B. | Constant K prototype filter |
| C. | Crystal filter |
| D. | Ceramic filters |
| Answer» D. Ceramic filters | |
| 8. |
_______ oscillators range from 20 kHz to 300 MHz. They can even be used for microwave applications as their capacitors provide low reactance path for the high frequency signals. |
| A. | Tuned collector |
| B. | Colpitts |
| C. | Wein bridge |
| D. | Hartley |
| Answer» C. Wein bridge | |
| 9. |
Direction: The following item consists of two statements, one labeled as ‘Statement (I)’ and the other as ‘Statement (II)’. Examine these two statements carefully and select the answers to these items using the code given below:Statement(I): Feedback compensation is preferred to series compensation. Statement(II): No amplification is required as the energy flows from a higher level to a lower level. |
| A. | Both Statement I and Statement II are individually true and Statement II is the correct explanation of Statement I |
| B. | Both Statement I and Statement II are individually true but Statement II is not the correct explanation of Statement I |
| C. | Statement I is true but Statement II is false |
| D. | Statement I is false but Statement II is true |
| Answer» B. Both Statement I and Statement II are individually true but Statement II is not the correct explanation of Statement I | |
| 10. |
Among the following, which is a fixed frequency oscillator? |
| A. | Crystal oscillator |
| B. | Phase-shift oscillator |
| C. | Hartley oscillator |
| D. | Colpitt's oscillator |
| Answer» B. Phase-shift oscillator | |
| 11. |
A Colpitts Oscillator is having tank capacitances of 1nF and 10nF, and inductance of 0.1μH. The gain required by the circuit to start oscillating is: |
| A. | 10 |
| B. | 100 |
| C. | 1 |
| D. | 1000 |
| Answer» B. 100 | |
| 12. |
In the RC Phase Displacement Oscillator, the total displacement of the three RC feedback networks is _____. |
| A. | 360° |
| B. | 90° |
| C. | 180° |
| D. | 0° |
| Answer» D. 0° | |
| 13. |
If LC components are used in the feedback path of an oscillator, the waveform generated is: |
| A. | sinusoidal wave at all frequencies |
| B. | triangular wave at all frequencies |
| C. | sinusoidal wave at radio frequencies |
| D. | square wave at radio frequencies |
| Answer» D. square wave at radio frequencies | |
| 14. |
R-C phase shift oscillator and Wein bridge oscillator are the commonly used circuits for generating ________ waveform of a required frequency. |
| A. | sine |
| B. | negative |
| C. | cosine |
| D. | both sine and cosine |
| Answer» B. negative | |
| 15. |
In which type of power amplifier does the output current flow for the entire cycle of input signal? |
| A. | Class C |
| B. | Class AB |
| C. | Class B |
| D. | Class A |
| Answer» E. | |
| 16. |
If L1 = 1 mH, L2 = 2 mH and C = 0.1 nF in Hartley oscillator, then f = ______ kHz. |
| A. | 145.57 |
| B. | 290.57 |
| C. | 45.88 |
| D. | 572.25 |
| Answer» C. 45.88 | |
| 17. |
For the non-inverting amplifiers as shown, find the closed-loop voltage gain. |
| A. | 100 |
| B. | 10 |
| C. | 101 |
| D. | 11 |
| Answer» E. | |
| 18. |
In an amplifier with input impedance Zi and output impedance Zo, when a current series feedback is introduced |
| A. | Zi increases, Zo decreases |
| B. | Zi decreases, Zo increases |
| C. | Zi increases, Zo increases |
| D. | Zi decreases, Zo decreases |
| Answer» D. Zi decreases, Zo decreases | |
| 19. |
A two stage amplifier with negative feedback |
| A. | can become unstable for larger values of β |
| B. | becomes unstable at high and very low frequencies if A is very large |
| C. | becomes unstable when the pole frequencies become complex |
| D. | is always stable |
| Answer» E. | |
| 20. |
For various types of oscillators, the correct statement is: |
| A. | LC oscillators are more stable than crystal oscillators |
| B. | Crystal oscillators have highest Q |
| C. | Phase-shift oscillators have the widest range of frequency |
| D. | Wien bridge oscillator is used where a single frequency oscillator is required |
| Answer» C. Phase-shift oscillators have the widest range of frequency | |
| 21. |
For the oscillator circuit shown in Fig., \(\dfrac{V_{out}}{V_f}=3+sCR+ \dfrac{1}{sCR}\).Its oscillating frequency and ratio \(\dfrac{R2}{R1}\) are respectively. |
| A. | \(\omega_0 = \dfrac{1}{\sqrt{3} \ RC} \ \rm rad/s, 2\) |
| B. | \(\omega_0 = \dfrac{1}{\sqrt{3} \ RC} \ \rm rad/s, 3\) |
| C. | \(\omega_0 = \dfrac{1}{RC} \ \rm rad/s, 3\) |
| D. | \(\omega_0 = \dfrac{1}{RC} \ \rm rad/s, 2\) |
| Answer» E. | |
| 22. |
Negative feedback of β = 2.5 × 10-3 is applied to an amplifier of open-loop gain 1000. What is the change in an overall gain of the feedback amplifier, if the gain of the internal amplifier is reduced by 20%? |
| A. | 295.7 |
| B. | 286.7 |
| C. | 275.7 |
| D. | 266.7 |
| Answer» E. | |
| 23. |
A Hartley oscillator is commonly used in ____. |
| A. | Radio Receivers |
| B. | Radio Transmitters |
| C. | TV Receivers |
| D. | TV Transmitters |
| Answer» B. Radio Transmitters | |
| 24. |
Keeping in view the stability of the control circuit the feedback factor (x) and gain without feedback (y) for a stable circuit are related as |
| A. | xy = 1 |
| B. | x/y < 1 |
| C. | xy < 1 |
| D. | x = y |
| Answer» D. x = y | |
| 25. |
Feedback in an amplifier always helps to ________ |
| A. | increase its gain |
| B. | decrease its input impedance |
| C. | stabilize its gain |
| D. | control its output |
| Answer» E. | |
| 26. |
A circuit using an OP - AMP shown in figure, has ______ |
| A. | Voltage series feedback |
| B. | Voltage shunt feedback |
| C. | Current shunt feedback |
| D. | Current series feedback |
| Answer» C. Current shunt feedback | |
| 27. |
In an amplifier with a gain of 1000 without feedback and cut-off frequencies at 2 kHz and 20 kHz, negative feedback of 1% is employed. The cut-off frequencies with feedback would be |
| A. | 220 Hz and 22 kHz |
| B. | 182 Hz and 220 kHz |
| C. | 220 kHz and 220 kHz |
| D. | 20 Hz and 22 kHz |
| Answer» C. 220 kHz and 220 kHz | |
| 28. |
Directions: It consists of two statements, one labeled as the ‘Statement (I)’ and the other as ‘Statement (II)’. Examine these two statements carefully and select the answer using the codes given below:Statement (I): A large negative feedback is deliberately introduced in an amplifier to make its gain independent of variation in parameters of active device and other components.Statement (II): A large negative feedback results in a high value of return difference compared to unity which makes the feedback gain inversely, proportional to feedback factor. |
| A. | Statement (I) and Statement (II) are individually true and statement (II) is the correct explanation of statement (II) |
| B. | Statement (I) and Statement (II) are individually true but statement (II) is not the correct explanation of statement (I) |
| C. | Statement (I) is true but statement (II) is false |
| D. | Statement (I) is false but statement (II) is true |
| Answer» B. Statement (I) and Statement (II) are individually true but statement (II) is not the correct explanation of statement (I) | |
| 29. |
An amplifier has input impedance of 4 kΩ and output impedance of 80 kΩ. It is used in negative feedback circuit with 10% feedback. If open loop gain is 90, the closed loop input and output impedances are |
| A. | 40 kΩ and 8 kΩ respectively |
| B. | 4 kΩ and 80 kΩ respectively |
| C. | 0.4 kΩ and 800 kΩ respectively |
| D. | 8 kΩ and 160 kΩ respectively |
| Answer» B. 4 kΩ and 80 kΩ respectively | |
| 30. |
A system has 3-stage cascaded amplifier, each stage having a power gain of 10 dB and noise figure of 6 dB. Overall noise figure is |
| A. | 1.38 |
| B. | 6.8 |
| C. | 4.33 |
| D. | 10.43 |
| Answer» D. 10.43 | |
| 31. |
If the voltage shunt negative feedback is applied to amplifier then bandwidth and input resistance ______ and _______ respectively. |
| A. | Decreases, Decreases |
| B. | Increases, Decreases |
| C. | Decreases, Increases |
| D. | Increases, Increases |
| Answer» C. Decreases, Increases | |
| 32. |
A power amplifier with a gain of 100 ∠ 0° has an output of 12 V at 1.5 kHz along with a second harmonic content of 25 percent. Negative feedback is to be provided to reduce the harmonic content of the output to 2-5 percent. What should be the gain of the feedback path and the level of the signal input to the overall system, respectively? |
| A. | 0.9 and 0.12 V |
| B. | 0.9 and 12 V |
| C. | 0.09 and 1.2 V |
| D. | 9 and 0.12 V |
| Answer» D. 9 and 0.12 V | |
| 33. |
Consider the following statements related to oscillator circuits :1. The tank circuit of a Hartley oscillator is made up of a tapped capacitor and a common inductor.2. The tank circuit of a Colpitts oscillator is made up of a tapped capacitor and a common oscillator.3. The Wien Bridge oscillator is essentially a two-stage amplifier with an RC bridge in the first stage, and, the second stage serving as an inverter.4. Crystal oscillators are fixed frequency oscillators with a high Q-factor. Which of the following are true? |
| A. | 1, 2 and 3 only |
| B. | 2, 3 and 4 only |
| C. | 1, 2 and 4 only |
| D. | 1, 3 and 4 only |
| Answer» C. 1, 2 and 4 only | |
| 34. |
Consider the following statements regarding Wien Bridge oscillator:1. It has a larger bandwidth than the phase shift oscillator.2. It has a smaller bandwidth than the phase shift oscillator.3. It has 2 capacitors while the phase shift oscillator has 3 capacitors.4. It has 3 capacitors while the phase shift oscillator has 2 capacitors.Which of the above statements are correct? |
| A. | 1 and 3 only |
| B. | 2 and 4 only |
| C. | 1 and 4 only |
| D. | 2 and 3 only |
| Answer» B. 2 and 4 only | |
| 35. |
For an RC phase shift oscillator, the following statements are cited:a) Amplifier gain is negativeb) Phase shift introduced by the feedback circuit is either 0 or 360°c) Amplifier gain is positived) Phase shift introduced by the feedback circuit is 180°Which of the following options is correct? |
| A. | Only a) is correct and rest are incorrect |
| B. | Only c) is correct and rest are incorrect |
| C. | Both a) and d) are correct |
| D. | Both b) and c) are correct |
| Answer» D. Both b) and c) are correct | |
| 36. |
Feedback factor is always |
| A. | zero |
| B. | less than 1 |
| C. | equal to 1 |
| D. | more than 1 |
| Answer» C. equal to 1 | |
| 37. |
In order to realize a current amplifier, the desired feedback topology will be |
| A. | series-series |
| B. | series-shunt |
| C. | shunt-series |
| D. | shunt-shunt |
| Answer» D. shunt-shunt | |