MCQOPTIONS
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MCQOPTIONS
This section includes 1136 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. |
The parameter β of a BJT change by 300%. If self bias is used in the amplifier using this BJT, the quiescent value of IC and VCE remain almost the same. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 2. |
Barkhausen criterion is 1 + Avβ = 0. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 3. |
When negative feedback is used the fractional changes in closed loop gain are desensitized by the factor (1 + Avβ) |
| A. | True |
| B. | False |
| Answer» B. False | |
| 4. |
A typical value of gm for a FET is about 25 μs. |
| A. | True |
| B. | False |
| Answer» C. | |
| 5. |
Assertion (A): The main use of positive feedback is in oscillator circuits.Reason (R): In an oscillator the loop gain Aβ is kept slightly more than unity |
| A. | Both A and R are correct and R is correct explanation for A |
| B. | Both A and R are correct but R is not correct explanation for A |
| C. | A is correct R is wrong |
| D. | A is wrong R is correct |
| Answer» C. A is correct R is wrong | |
| 6. |
Assertion (A): In Darlington pair, the overall β is product of individual βsReason (R): The voltage gain of a base driven amplifier is equal to ac collector voltage divided by ac base voltage |
| A. | Both A and R are correct and R is correct explanation for A |
| B. | Both A and R are correct but R is not correct explanation for A |
| C. | A is correct R is wrong |
| D. | A is wrong R is correct |
| Answer» C. A is correct R is wrong | |
| 7. |
Assertion (A): In class A amplifier the distortion is minimumReason (R): In class A amplifier collector current exists for 360° of input cycle |
| A. | Both A and R are correct and R is correct explanation for A |
| B. | Both A and R are correct but R is not correct explanation for A |
| C. | A is correct R is wrong |
| D. | A is wrong R is correct |
| Answer» B. Both A and R are correct but R is not correct explanation for A | |
| 8. |
Assertion (A): A class C amplifier is a timed amplifier which needs a tank circuit as the load in the collector circuit of the transistor for its proper operationReason (R): In class C operation collector current flows for less than 180° of the ac cycle and thus flows in pulses |
| A. | Both A and R are correct and R is correct explanation for A |
| B. | Both A and R are correct but R is not correct explanation for A |
| C. | A is correct R is wrong |
| D. | A is wrong R is correct |
| Answer» B. Both A and R are correct but R is not correct explanation for A | |
| 9. |
For oscillations to starts, the loop gain A β of the oscillator must be initially |
| A. | less than unity |
| B. | 0.5 |
| C. | 1 |
| D. | more than unity |
| Answer» E. | |
| 10. |
In a Hartley oscillator the condition for sustained oscillations is . If there exists mutual inductance M between coils L1 and L2, then the above condition will get modified as hfe |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» D. [D]. | |
| 11. |
In a practical oscillator, the magnitude of loop gain Aβ is kept slightly larger than unity and the amplitude of oscillations is limited by |
| A. | the ratio of A to β |
| B. | the on set of non-linearity of amplifying device |
| C. | the linearity of amplifying device |
| D. | all of the above |
| Answer» C. the linearity of amplifying device | |
| 12. |
A three-section RC phase shift oscillator has R = 10K ohms and C = 0.001 μF. If the oscillator is to be made variable using the same value of R, what should be the value of capacitor to obtain a frequency if 1 kHz? |
| A. | 636 pF |
| B. | 180 pF |
| C. | 65 pF |
| D. | 30 pF |
| Answer» D. 30 pF | |
| 13. |
A three-section RC phase shift oscillator has R = 10K ohms and C = 0.001 μF. The frequency of oscillations is |
| A. | 1.1 kHz |
| B. | 2.5 kHz |
| C. | 3.3 kHz |
| D. | 6.5 kHz |
| Answer» E. | |
| 14. |
When a transistor is to be at a temperature above 25°C |
| A. | smaller heat sink be provided |
| B. | maximum power rating be derated |
| C. | biasing circuit must be strengthened |
| D. | earth connections must be connected through a resistor |
| Answer» C. biasing circuit must be strengthened | |
| 15. |
The signal input to a given amplifier is made up of 100 mΩ signal power and 1 mΩ noise power. The amplifier contributes an additional 100 mΩ of noise and has a power gain of 20 dB. The output signal-to-noise ratio is |
| A. | 100 |
| B. | 50 |
| C. | 10 |
| D. | 5 |
| Answer» C. 10 | |
| 16. |
The signal input to a given amplifier is made up of 100 mΩ signal power and 1 mΩ noise power. The amplifier contributes an additional 100 mΩ of noise and has a power gain of 20 dB. The noise factor is |
| A. | 1 |
| B. | 1.5 |
| C. | 2 |
| D. | 15 |
| Answer» D. 15 | |
| 17. |
The signal input to a given amplifier is made up of 100 mΩ signal power and 1 mΩ noise power. The amplifier contributes an additional 100 mΩ of noise and has a power gain of 20 dB. The input signal-to noise ratio is |
| A. | 2 |
| B. | 10 |
| C. | 20 |
| D. | 100 |
| Answer» E. | |
| 18. |
A generator with an internal resistance of 600 Ω drives an amplifier whose input resistance is 400 Ω. The generator's open circuit voltages is 1 mV; the amplifier develops 100mV across an 8kΩ load. The power gain is |
| A. | 125 |
| B. | 250 |
| C. | 1125 |
| D. | 3125 |
| Answer» E. | |
| 19. |
A generator with an internal resistance of 600 Ω drives an amplifier whose input resistance is 400 Ω. The generator's open circuit voltages is 1 mV; the amplifier develops 100mV across an 8kΩ load. The voltage multiplication is |
| A. | 25 |
| B. | 50 |
| C. | 125 |
| D. | 250 |
| Answer» E. | |
| 20. |
A generator with an internal resistance of 600 Ω drives an amplifier whose input resistance is 400 Ω. The generator's open circuit voltages is 1 mV; the amplifier develops 100mV across an 8kΩ load. The current amplification is |
| A. | 2.5 |
| B. | 12.5 |
| C. | 25 |
| D. | 125 |
| Answer» C. 25 | |
| 21. |
A generator with an internal resistance of 600 Ω drives an amplifier whose input resistance is 400 Ω. The generator's open circuit voltages is 1 mV; the amplifier develops 100mV across an 8kΩ load. The input voltage to the amplifier is |
| A. | 0.1 m V |
| B. | 0.4 m V |
| C. | 1 m V |
| D. | 4 m V |
| Answer» C. 1 m V | |
| 22. |
In an amplifier, if the output current flows for 120° of the input cycle, the class of amplifier will be |
| A. | A |
| B. | B |
| C. | C |
| D. | AB |
| Answer» D. AB | |
| 23. |
For a transistor to have-a larger β it must have and a |
| A. | close to zero |
| B. | close to 0.5 |
| C. | close to unity |
| D. | nearly infinite |
| Answer» D. nearly infinite | |
| 24. |
In an amplifier if conductor during the cycle is from 0 to 90° and again from 180° to 270°, the amplifier will be termed as |
| A. | class A |
| B. | class B |
| C. | class C |
| D. | class AB |
| Answer» C. class C | |
| 25. |
Two 3Ω speakers in series will have a total impedance of |
| A. | 1 Ω |
| B. | [B]. |
| C. | 3 Ω |
| D. | 6 Ω |
| Answer» C. 3 Ω | |
| 26. |
The minimum gate source voltage that creates the n-type inversion layer is called |
| A. | cut off voltage |
| B. | on voltage |
| C. | threshold voltage |
| D. | zener voltage |
| Answer» D. zener voltage | |
| 27. |
The bandwidth of an amplifier is BW, of n-stage of such as amplifier are cascaded, the bandwidth will become |
| A. | n BW |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» E. | |
| 28. |
Which of the following plot can be directly used to determine β? |
| A. | VCE versus iC for constant IB |
| B. | VBE versus iB for constant VCE |
| C. | VCB versus iC for constant IB |
| D. | All of the above |
| Answer» B. VBE versus iB for constant VCE | |
| 29. |
A certain transistor has adc of 0.98 and a collectors leakage current of 5 μA. If IE = 1 mA, the base current will be |
| A. | 35 μA |
| B. | 25 μA |
| C. | 15 μA |
| D. | 5 μA |
| Answer» D. 5 μA | |
| 30. |
A certain transistor has adc of 0.98 and a collectors leakage current of 5 μA. If IE = 1 mA, the collector current will be |
| A. | 1.005 mA |
| B. | 0.985 mA |
| C. | 0.975 mA |
| D. | 0.955 mA |
| Answer» C. 0.975 mA | |
| 31. |
A transistor has collectoremitterbase In a N-P-N transistor the electron flow into the transistor at |
| A. | I only |
| B. | II only |
| C. | II and III only |
| D. | I and II only |
| Answer» E. | |
| 32. |
In a N-P-N transistor the function of the emitter is |
| A. | to emit or inject holes into the collector |
| B. | to emit or inject electrons into the collector |
| C. | to emit or inject electrons into the base |
| D. | to emit or inject holes into the base |
| Answer» D. to emit or inject holes into the base | |
| 33. |
The input differential stage of op-amp. 741 is baised at about 10 μA current such a low current of the input stage gives high CMRRhigh differential gainlow differentialhigh input impedance Which of these are correct? |
| A. | 1 and 2 |
| B. | 1, 2 and 4 |
| C. | 3 and 4 |
| D. | 1, 2, 3 and 4 |
| Answer» C. 3 and 4 | |
| 34. |
In the circuit shown in the given figure, the current flowing through resistance of 100 Ω would be |
| A. | 8 mA |
| B. | 10 mA |
| C. | 20 mA |
| D. | 100 mA |
| Answer» B. 10 mA | |
| 35. |
The voltage gains of an amplifier without feedback and with negative feedback respectively are 100 and 20. The percentage of negative feedback (β) would be |
| A. | 40% |
| B. | 5% |
| C. | 20% |
| D. | 80% |
| Answer» B. 5% | |
| 36. |
The given circuit has a feedback factor of |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» E. | |
| 37. |
The ripple factor of a power supply is given by |
| A. | Pdc/Pac |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» C. [C]. | |
| 38. |
For a transistor amplifier with self biasing network, the following components are used. R1 = 4 kΩ, R2 = 4 kΩ, RC = 1 kΩ. The approximate value of the stability factor 'S' will be |
| A. | 4 |
| B. | 3 |
| C. | 2 |
| D. | 1.5 |
| Answer» C. 2 | |
| 39. |
If Rs is the sources resistance, the O/P resistance of an emitter follower using the simplified hybrid model would be |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» B. [B]. | |
| 40. |
In the case of the circuit shown in the figure, the collector current IC will be, if β = 100, VBE = 0.7 V, ICO = 0.1 βA at 20°C |
| A. | 2.26 mA |
| B. | 1.85 mA |
| C. | 0.357 mA |
| D. | 0.185 mA |
| Answer» B. 1.85 mA | |
| 41. |
For an I/p of Vs = 5 sin ωt (assuming ideal diode), circuit shown in the figure will behave as a |
| A. | clipper, sine wave clipped at -2 V |
| B. | clamper, sine wave clamped at -2 V |
| C. | clamper, sine wave clamped at 0 volts |
| D. | clipper, sine wave clipped at 2 V |
| Answer» C. clamper, sine wave clamped at 0 volts | |
| 42. |
The 'h' parameters of the circuit shown in the figure are hib = 25 Ω, hfb = 0.999 and hob = 10-6Ω The Voltage gain is |
| A. | 0.99 |
| B. | 1.98 |
| C. | 2 |
| D. | 4 |
| Answer» E. | |
| 43. |
If an amplifier with gain of - 1000 and feedback factor β = - 0.1 had a gain change of 20% due to temperature, the change in gain of the feedback amplifier would be |
| A. | 10% |
| B. | 5% |
| C. | 0.2% |
| D. | 0.01% |
| Answer» D. 0.01% | |
| 44. |
Leakage current approximately doubles for every 10°C increase in the temperature of a transistor has ICBO = 400 nA at 25°C, then its leakage current at 80°C |
| A. | 10 μA |
| B. | 18 μA |
| C. | 20 μA |
| D. | 15 μA |
| Answer» C. 20 μA | |
| 45. |
In following figure find VDSQ by assuming gate current is negligible for the p-channel JFET. (if IDQ = - 6 mA, RS = 0, VDD = -18 V, RD = 2 kΩ, IDSS = - 10 mA, IPO = - 3 V) |
| A. | 4 V |
| B. | - 6 V |
| C. | - 10 V |
| D. | 6 V |
| Answer» C. - 10 V | |
| 46. |
In following figure find VGG by assuming gate current is negligible for the p-channel JFET. (if IDQ = - 6 mA, RS = 0, VDD = -18 V, RD = 2 kΩ, IDSS = - 10 mA, IPO = - 3 V) |
| A. | 0.67 V |
| B. | 6.7 V |
| C. | 7 V |
| D. | 0.3 V |
| Answer» B. 6.7 V | |
| 47. |
In following figure, what will be R1 and R2 for maximum symmetrical swing if VCSat ≈ 0. Given that RE = 200 Ω, RC = 400 Ω, VCC = 20 V, β = 99 |
| A. | 6 k |
| B. | 3 k, 6 k |
| C. | 9.9 k, 2.4 k |
| D. | 2.4 k, 9.9 k |
| Answer» E. | |
| 48. |
In following circuit, RB will be if VCC = 10 V, VS = 2 V, RC = 5 kΩ, RS = 90 kΩ, β = 50, ICE = 0, VCEsat = 0.1 V |
| A. | 230 K |
| B. | 235 K |
| C. | 240 K |
| D. | 250 K |
| Answer» C. 240 K | |
| 49. |
The transistor of following figure in Si diode with a base current of 40 μA and ICBO = 0, if VBB = 6V, RE = 2 kΩ and β = 90, IBQ = 20 μA then RB = |
| A. | 200 kΩ |
| B. | 265 kΩ |
| C. | 150 kΩ |
| D. | 100 kΩ |
| Answer» C. 150 kΩ | |
| 50. |
A transistor with a = 0.98 then β will be |
| A. | 49 |
| B. | 50 |
| C. | 47 |
| D. | 48 |
| Answer» B. 50 | |