MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 14 Mcqs, each offering curated multiple-choice questions to sharpen your Electronic Devices knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
In a class B push-pull amplifier, crossover distortion occurs when both transistors are off and the input signal voltage must exceed V before a transistor conducts. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 2. |
The highest efficiency is obtained in class B operation when the level of V(p) is equal to ________. |
| A. | 0.25V |
| B. | 0.50V |
| C. | V |
| D. | 2V |
| Answer» D. 2V | |
| 3. |
In a class A transformer-coupled amplifier, the ________ the value of V and the ________ the value of V, the ________ the efficiency to (from) the theoretical limit of 50%. |
| A. | larger, smaller, farther |
| B. | larger, smaller, closer |
| C. | smaller, larger, closer |
| D. | None of the above |
| Answer» C. smaller, larger, closer | |
| 4. |
Calculate V. |
| A. | 0 V |
| B. | 0.7 V |
| C. | 9.3 V |
| D. | 10.7 V |
| Answer» D. 10.7 V | |
| 5. |
A silicon power transistor is operated with a heat sink ( = 1.5ºC/W). The transistor, rated at 150 W (25ºC), has = 0.5º C/W, and the mounting insulation has = 0.6 ºC/W. What is the maximum power that can be dissipated if the ambient temperature is 50ºC and T = 200 ºC? |
| A. | 61.5 W |
| B. | 60.0 W |
| C. | 57.7 W |
| D. | 55.5 W |
| Answer» D. 55.5 W | |
| 6. |
Refer to this figure. The dc voltage on the collector, V, is |
| A. | 5.4 V. |
| B. | 6.6 V. |
| C. | 12 V. |
| D. | 0 V. |
| Answer» B. 6.6 V. | |
| 7. |
In class B operation, at what fraction of V should the level of V(p) be to achieve the maximum power dissipated by the output transistor? |
| A. | 0.5 |
| B. | 0.636 |
| C. | 0.707 |
| D. | 1 |
| Answer» C. 0.707 | |
| 8. |
What transformer turns ratio is required to match an 8- speaker load so that the effective load resistance seen at the primary is 12.8 k? |
| A. | 20:1 |
| B. | 40:1 |
| C. | 50:1 |
| D. | 60:1 |
| Answer» C. 50:1 | |
| 9. |
In a class AB amplifier, if the V drops are not matched to the diode drops or if the diodes are not in thermal equilibrium with the transistors, this can result in |
| A. | a current mirror. |
| B. | diode separation. |
| C. | crossover distortion. |
| D. | thermal runaway. |
| Answer» E. | |
| 10. |
Calculate the effective resistance seen looking into the primary of a 20:1 transformer connected to an 8- load. |
| A. | 3.2 k |
| B. | 3.0 k |
| C. | 2.8 k |
| D. | 1.8 k |
| Answer» B. 3.0 k | |
| 11. |
A class A amplifier with R = 3.3 k and R = 1.2 k has a V = 20 V. Find I. |
| A. | 4.4 mA |
| B. | 6.1 mA |
| C. | 16.7 mA |
| D. | 20 mA |
| Answer» B. 6.1 mA | |
| 12. |
Calculate the efficiency of a class B amplifier for a supply voltage of V = 20 V with peak output voltage of V(p) = 18 V. Assume R = 16 |
| A. | 78.54% |
| B. | 75% |
| C. | 70.69% |
| D. | 50% |
| Answer» D. 50% | |
| 13. |
MOS and MOS transistors can be used for class B. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 14. |
Determine V. |
| A. | 0 V |
| B. | 0.7 V |
| C. | 9.3 V |
| D. | 10.7 V |
| Answer» E. | |