MCQOPTIONS
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MCQOPTIONS
This section includes 20 Mcqs, each offering curated multiple-choice questions to sharpen your Power Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The triac is similar to an SCR, but it provides conduction for both halves of the ac wave. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 2. |
The anode-to-gate voltage can be used to turn the PUT on or off. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 3. |
UJTs can only be used to trigger triacs, not SCRs. |
| A. | True |
| B. | False |
| Answer» C. | |
| 4. |
In an SCR-based half-wave phase-control circuit, a diode is connected in series with the anode. |
| A. | True |
| B. | False |
| Answer» C. | |
| 5. |
The SCS is turned on with the cathode gate, and turned off with the anode gate. |
| A. | True |
| B. | False |
| Answer» C. | |
| 6. |
The triac can be turned on or off by a pulse at the gate. |
| A. | True |
| B. | False |
| Answer» C. | |
| 7. |
The SUS is also known as a Shockley diode. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 8. |
The diac can conduct current in either direction and is turned on when a breakover voltage is exceeded. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9. |
The SCR is a device that can be triggered off by a pulse applied to the gate. |
| A. | True |
| B. | False |
| Answer» C. | |
| 10. |
Thyristors are 4-layer semiconductor devices. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 11. |
You have a light-dimmer circuit using an SCR. In testing the circuit, you find that IG = 0 mA and the light is still on. You conclude that the trouble might be one of the following: |
| A. | the SCR is open. |
| B. | the switch is faulty. |
| C. | the gate circuit is shorted. |
| D. | this is normal; nothing is wrong. |
| Answer» E. | |
| 12. |
Identify the triac from the given figures. |
| A. | a |
| B. | b |
| C. | c |
| D. | d |
| E. | e |
| Answer» F. | |
| 13. |
THE_GATE_CHARACTERISTICS_OF_THYRISTOR_IS_A_PLOT_OF?$ |
| A. | V<sub>g</sub> on the X-axis & I<sub>g</sub> on the Y-axis |
| B. | I<sub>g</sub> on the X-axis & V<sub>g</sub> on the Y-axis |
| C. | V<sub>a</sub> on the X-axis & I<sub>g</sub> on the Y-axis |
| D. | I<sub>g</sub> on the X-axis & V<sub>a</sub> on the Y-axis |
| Answer» C. V<sub>a</sub> on the X-axis & I<sub>g</sub> on the Y-axis | |
| 14. |
The_area_under_the_curve_of_the_gate_characteristics_of_thyristor_gives_the$ |
| A. | total average gate current |
| B. | total average gate voltage |
| C. | total average gate impedance |
| D. | total average gate power dissipation |
| Answer» E. | |
| 15. |
To avoid commutation failur? |
| A. | circuit turn-off time must be greater than the thyristor turn-off time |
| B. | circuit turn-off time must be lesser than the thyristor turn-off time |
| C. | circuit turn-off time must be equal to the thyristor turn-off time |
| D. | none of the above mentioned |
| Answer» B. circuit turn-off time must be lesser than the thyristor turn-off time | |
| 16. |
For effective turning off of the SCR after the anode current has reached zero value, ______________ |
| A. | chargers are injected by applying reverse anode-cathode voltage |
| B. | chargers are removed by applying reverse anode-cathode voltage |
| C. | chargers are injected by applying gate signal |
| D. | chargers are removed by applying gate signal |
| Answer» C. chargers are injected by applying gate signal | |
| 17. |
The latching current is _________ than the holding current |
| A. | lower |
| B. | higher |
| C. | same as |
| D. | negative of |
| Answer» C. same as | |
| 18. |
The minimum value of anode current below which it must fall to completely turn-off the device is called as the |
| A. | holding current value |
| B. | latching current value |
| C. | switching current value |
| D. | peak anode current value |
| Answer» B. latching current value | |
| 19. |
For an SCR the total turn-on time consists of |
| A. | Delay time |
| B. | Rise time and |
| C. | Spread time |
| Answer» B. Rise time and | |
| 20. |
During the transition time or turn-on time |
| A. | The forward anode voltage decreases from 90 % to 10 % & the anode current also decreases from 90 to 10 % of the initial value |
| B. | The forward anode voltage increases from 10 % to 90 % & the anode current also increases from 10 % to 90 % of the initial value |
| C. | The forward anode voltage decreases from 90 % to 10 % & the anode current increases from 10 % to 90 % of the initial value |
| D. | The forward anode voltage increases from 10 % to 90 % & the anode current decreases from 90% to 10% of the initial value |
| Answer» D. The forward anode voltage increases from 10 % to 90 % & the anode current decreases from 90% to 10% of the initial value | |