MCQOPTIONS
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MCQOPTIONS
This section includes 74 Mcqs, each offering curated multiple-choice questions to sharpen your Electronic Devices Circuits knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The transfer of a signal in a transistor is_________ |
| A. | low to high resistance |
| B. | high to low resistance |
| C. | collector to base junction |
| D. | emitter to base junction |
| Answer» B. high to low resistance | |
| 2. |
If the emitter-base junction is forward biased and the collector-base junction is reverse biased, what will be the region of operation for a transistor? |
| A. | cut off region |
| B. | saturated region |
| C. | inverted region |
| D. | active region |
| Answer» E. | |
| 3. |
When does the transistor act like an open switch? |
| A. | cut off region |
| B. | inverted region |
| C. | saturated region |
| D. | active region |
| Answer» B. inverted region | |
| 4. |
If α = 0.995, IE = 10 mA and ICO = 0.5 μA, then the value of ICEO is: |
| A. | 100 μA |
| B. | 10.1 μA |
| C. | 10.5 μA |
| D. | 25 μA |
| Answer» B. 10.1 μA | |
| 5. |
A bipolar junction transistor with forward current transfer ratio α = 0.98, when working in CE mode, provides current transfer |
| A. | 98 |
| B. | 0.02 |
| C. | 49 |
| D. | 0.49 |
| Answer» D. 0.49 | |
| 6. |
Consider a common-emitter current gain of β = 150 and a base current of iB = 15 μA. If the transistor is biased in the forward active mode, the collector and emitter current will be |
| A. | 2.25 mA and 2.27 mA |
| B. | 3.25 mA and 2.27 mA |
| C. | 2.25 mA and 1.37 mA |
| D. | 3.25 mA and 1.37 mA |
| Answer» B. 3.25 mA and 2.27 mA | |
| 7. |
If an NPN transistor is properly biased in the active region, then most of the electrons from the emitter |
| A. | recombine with holes in the base |
| B. | recombine in the emitter itself |
| C. | are stopped by the junction barrier |
| D. | pass through the base to the collector |
| Answer» E. | |
| 8. |
A BJT with β = 50 has a base to collector leakage current ICBO of 2.5 μA. If the transistor is connected in CE configuration, the collector current for IB = 0 is |
| A. | 0.05 μA |
| B. | 0.1275 mA |
| C. | 0.157 mA |
| D. | 0.516 mA |
| Answer» C. 0.157 mA | |
| 9. |
In a transistor, the base current and collector current are, respectively, 60 μA and 1.75 mA. The value of α is nearly |
| A. | 0.91 |
| B. | 0.97 |
| C. | 1.3 |
| D. | 1.7 |
| Answer» C. 1.3 | |
| 10. |
A transistor has a βDC of 60 and a base current, IB, of 20 µA. The collector current, IC, equals |
| A. | 0.3 µA |
| B. | 1200 µA |
| C. | 1220 µA |
| D. | 120 µA |
| Answer» C. 1220 µA | |
| 11. |
α-cut off frequency of a bipolar junction transistor increases __________. |
| A. | with the increase in base width |
| B. | with the increase in collector width |
| C. | with the increase in temperature |
| D. | with the decrease in base width |
| Answer» E. | |
| 12. |
Directions: Each of the given items consist of two statements, one labeled as the ‘Statement (I)’ and the other as ‘Statement (II)’. Examine these two statements carefully and select the answers to these items using the codes given below:Statement (I): The β of a bipolar transistor is reduced if the base width is increased.Statement (II): The β of a bipolar transistor increases, if the doping concentration in the base is increased.Codes: |
| 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 mot 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» D. Statement (I) is false but Statement (II) is true. | |
| 13. |
Consider the recombination process via bulk traps in a forward-biased pn homojunction diode. The maximum recombination rate is Umax. If the electron and the hole capture cross-sections are equal, which one of the following is FALSE? |
| A. | With all other parameters unchanged, Umax decreases if the intrinsic carrier density is reduced. |
| B. | Umax occurs at the edges of the depletion region in the device. |
| C. | Umax depends exponentially on the applied bias. |
| D. | With all other parameters unchanged, Umax increases if the thermal velocity of the carriers increases. |
| Answer» C. Umax depends exponentially on the applied bias. | |
| 14. |
A transistor connected in a common base configuration has the following readings IE = 2 mA and IB = 20 μA. Find the current gain α. |
| A. | 0.95 |
| B. | 1.98 |
| C. | 0.99 |
| D. | 0.98 |
| Answer» D. 0.98 | |
| 15. |
For a uniformly doped NPN transistor, find the approximate emitter injection efficiency.Given that:NE = 2 × 1018 cm-3, NB = 1017 cm-3, NC = 4 × 1019 cm-3, DE = 8 cm2/s, DC = 28 cm2/s, DB = 20 cm2/s, xE = 0.5 μm, xB = 0.3 μm. |
| A. | 0.95 |
| B. | 0.92 |
| C. | 0.99 |
| D. | 0.94 |
| Answer» D. 0.94 | |
| 16. |
Directions: Each of the next items consists of two statements, one labeled as the `Assertion (A)' and the other as 'Reason (R)' You are to examine these two statements carefully and select the answers to these items using the codes given below :Assertion (A): In a transistor, it is desirable that the carriers contributing to emitter current in the active mode reach the collector terminal.Reason (R): The conductivity of the base in a transistor is made much smaller than the conductivity of the emitter. |
| A. | Both A and R are individually true and R is the correct explanation of A |
| B. | Both A and R are individually true but R is not the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are individually true but R is not the correct explanation of A | |
| 17. |
Calculate the value of IE for a BJT with αdc = 0.99 and IB = 40 μA |
| A. | 8.0 mA |
| B. | 5.0 mA |
| C. | 4.0 mA |
| D. | 9.9 mA |
| Answer» D. 9.9 mA | |
| 18. |
In a transistor which of the following region is very lightly doped and is very thin |
| A. | emitter |
| B. | base |
| C. | collector |
| D. | None of these |
| Answer» C. collector | |
| 19. |
BJT is a _____ |
| A. | Voltage controlled device |
| B. | Current controlled device |
| C. | Very high input impedance device |
| D. | None of the above |
| Answer» C. Very high input impedance device | |
| 20. |
In BJT when both the junctions are forward biased, then its operating mode is called: |
| A. | forward active mode |
| B. | cut-off mode |
| C. | saturation mode |
| D. | reverse active mode |
| Answer» D. reverse active mode | |
| 21. |
An npn BJT is operating in the active region. If the reverse bias across the base-collector junction is increased, then |
| A. | The effective base width increases and common-emitter current gain increases |
| B. | The effective base width increases and common-emitter current gain decreases |
| C. | The effective base width decreases and common-emitter current gain increases |
| D. | The effective base width decreases and common-emitter current gain decreases |
| Answer» D. The effective base width decreases and common-emitter current gain decreases | |
| 22. |
A lateral pnp device has base width of 10 μm and diffusion coefficient for base region is 20cm2/sec. the base transit time is _______. |
| A. | 50 ns |
| B. | 2 ns |
| C. | 25 ns |
| D. | 1 ns |
| Answer» D. 1 ns | |
| 23. |
In a BJT, collector region width is maximum when it.1. Collects maximum number of charge carrier2. Reduces heat dissipation per unit area Out of these |
| A. | Only 1 is correct |
| B. | Only 2 is correct |
| C. | Both 1 and 2 are correct |
| D. | Neither 1 nor 2 incorrect |
| Answer» D. Neither 1 nor 2 incorrect | |
| 24. |
In a transistor, if the current gain is 100 and the collector current is 5 mA, the base current is |
| A. | 5 μA |
| B. | 50 mA |
| C. | 500 mA |
| D. | 50 μA |
| Answer» E. | |
| 25. |
An increase in the base recombination of a BJT will increase |
| A. | the common-emitter dc current gain β |
| B. | the breakdown voltage BVCEO |
| C. | the unity gain cut-off frequency fT |
| D. | the transconductance gm |
| Answer» C. the unity gain cut-off frequency fT | |
| 26. |
For a transistor with βDC of 250 and a base current IB of 20 micro A, the collector current IC equals: |
| A. | 500 micro A |
| B. | 5 milli A |
| C. | 50 milli A |
| D. | 5 A |
| Answer» C. 50 milli A | |
| 27. |
For a base current of 10 μA, what is the value of collector current in common emitter if βdc = 100 |
| A. | 10 μA |
| B. | 100 μA |
| C. | 1 mA |
| D. | 10 mA |
| Answer» D. 10 mA | |
| 28. |
In which of the following bias circuit, the stability factor is dependent upon RC? |
| A. | Fixed bias |
| B. | Collector to base bias |
| C. | Emitter bias |
| D. | Self bias |
| Answer» C. Emitter bias | |
| 29. |
If the base width in a bipolar junction transistor is doubled, which one of the following statements will be TRUE? |
| A. | The current gain will increase. |
| B. | Unity gain frequency will increase. |
| C. | Emitter-base junction capacitance will increase. |
| D. | Early Voltage will increase. |
| Answer» E. | |
| 30. |
In common-collector configuration of bipolar junction transistor (BJT), the output voltage is: |
| A. | in phase with the input voltage |
| B. | shifted by 270° from the input voltage |
| C. | out of phase with the input voltage |
| D. | shifted by 90° from the input voltage |
| Answer» B. shifted by 270° from the input voltage | |
| 31. |
For a BJT, IC = 5 mA, IB = 50 μA and ICBO = 0.5 μA, then the value of β is |
| A. | 99 |
| B. | 91 |
| C. | 79 |
| D. | 61 |
| Answer» B. 91 | |
| 32. |
Direction: Question consists of two statements, one labeled as the 'Assertion (A)' and the other as 'Reason (R)'. Examine these two statements carefully and select the answer to this question using the codes given below:Assertion (A): The short-circuit current gain of a bipolar junction transistor, in common base configuration increases with an increase in the reverse bias collector to base voltage.Reason (R): With an increase in the reverse bias collector to base voltage, the effective base width decreases. |
| A. | Both A and R are individually true and R is the correct explanation of A |
| B. | Both A and R are individually true but R is not the correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are individually true but R is not the correct explanation of A | |
| 33. |
For transistor action: |
| A. | the collector must be heavily doped than the emitter region |
| B. | the collector base junction must be forward biased |
| C. | the base region must be narrow |
| D. | the base region must be N-type material |
| Answer» D. the base region must be N-type material | |
| 34. |
In common emitter configuration of a transistor circuit, the common-emitter forward amplification factor is given by the ratio: |
| A. | \(\frac{{{I_C}}}{{{I_B}}}\) |
| B. | \(\frac{{{I_E}}}{{{I_B}}}\) |
| C. | \(\frac{{{I_C}}}{{{I_E}}}\) |
| D. | \(\frac{{{I_B}}}{{{I_E}}}\) |
| Answer» B. \(\frac{{{I_E}}}{{{I_B}}}\) | |
| 35. |
Four relations are given below. Identify the correct relation regarding a transistor. |
| A. | IE < IC > IB |
| B. | IE + IC = IB |
| C. | IE > IC < IB |
| D. | IE > IC > IB |
| Answer» E. | |
| 36. |
Most of the electrons in the base of an NPN transistor flow |
| A. | out of the base lead |
| B. | into the collector |
| C. | into the base |
| D. | into the base supply |
| Answer» C. into the base | |
| 37. |
A transistor has an emitter current of 8 mA and α of 0.99. Which of the following could be the collector current? |
| A. | 7.92 mA |
| B. | 5.00 mA |
| C. | 8.1 mA |
| D. | 7.84 mA |
| Answer» B. 5.00 mA | |
| 38. |
In bipolar I. C. technology, the n – p – n transistors have the following regions:(i) Emitter(ii) Base(iii) Collector(iv) SubstrateArrange them in ascending order of their resistance offered. |
| A. | (i), (ii), (iii), (iv) |
| B. | (ii), (iii), (iv), (i) |
| C. | (iii), (iv), (i), (ii) |
| D. | (iv), (i), (ii), (iii) |
| Answer» B. (ii), (iii), (iv), (i) | |
| 39. |
For a narrow base PNP BJT, the excess minority carrier concentrations (ΔnE for emitter, ΔpB for base, ΔnC for collector) normalized to equilibrium minority carrier concentrations (nE0 for emitter, pB0 for base, nC0 for collector) in the quasi-neutral emitter, base and collector regions are shown below. Which one of the following biasing modes is the transistor operating in? |
| A. | Forward active |
| B. | Saturation |
| C. | Inverse active |
| D. | Cutoff |
| Answer» D. Cutoff | |
| 40. |
In a junction transistor, recombination of electrons and holes occurs in |
| A. | base region only |
| B. | emitter region only |
| C. | collector region only |
| D. | all the 3 regions |
| Answer» B. emitter region only | |
| 41. |
If ICEO = 410 μA, ICBO = 5 μA and IB = 30 μA, then the collector current is: |
| A. | 415 mA |
| B. | 440 mA |
| C. | 445 mA |
| D. | 2.84 mA |
| Answer» E. | |
| 42. |
If α = 0.995m IE = 10 mA and Ico= 0.5 μA then ICEO will be |
| A. | 25 μA |
| B. | 100 μA |
| C. | 10.1 mA |
| D. | 0.5 mA |
| Answer» C. 10.1 mA | |
| 43. |
Figure shown below represents a |
| A. | A power diode |
| B. | Zener Diode |
| C. | NPN Transistor |
| D. | PNP Transistor |
| Answer» E. | |
| 44. |
If an input signal ranges from 20 μA – 40 μA with an output signal ranging from 0.5 mA – 1.5 mA, what is the βa.c. ? |
| A. | 0.05 |
| B. | 20 |
| C. | 50 |
| D. | 500 |
| Answer» D. 500 | |
| 45. |
If the collector current of a transistor is 10 mA and the base current is 100 μA, then what is its beta? |
| A. | 10 |
| B. | 100/101 |
| C. | 100 |
| D. | 1 |
| Answer» D. 1 | |
| 46. |
In a transistor, β may be expressed in terms of α as below: |
| A. | α/(1 – α) |
| B. | α/(1 + α) |
| C. | (1 - α)/α |
| D. | (1 + α)/α |
| Answer» B. α/(1 + α) | |
| 47. |
In a pnp transistor operating in the active region; in the base region, the main stream of current is |
| A. | Drift of holes |
| B. | Diffusion of holes |
| C. | Drift of electrons |
| D. | Diffusion of electrons |
| Answer» C. Drift of electrons | |
| 48. |
In a UJT, an intrinsic standoff ratio, n is typically: |
| A. | 0.2 |
| B. | 0.4 |
| C. | 0.7 |
| D. | 0.99 |
| Answer» D. 0.99 | |
| 49. |
For a BJT, α = 0.97 and collector base junction reverse saturation current is given by 0.4 μA. This BJT is connected in common emitter configuration and operating in active region. If IB = 15 μA then the collector current for the device will be _________ |
| A. | 506 μA |
| B. | 498.34 μA |
| C. | 101 mA |
| D. | 1 mA |
| Answer» C. 101 mA | |
| 50. |
If a transistor is operated in such a way that output current flow for 60 degrees of the input signal, it is |
| A. | Class A operation |
| B. | Class B operation |
| C. | Class C operation |
| D. | None of these |
| Answer» D. None of these | |