Power Electronics

11. A triac is equivalent to two SCRs __________

1. In parallel
2. In series
3. In inverse-parallel
4. None of the above

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12. A UJT has __________

1. Two pn junctions
2. One pn junction
3. Three pn junctions
4. None of the above

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13. A UJT is sometimes called __________ diode

1. Low resistance
2. High resistance
3. Single-base
4. Double-base

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14. After peak point, the UJT operates in the __________ region

1. Cut-off
2. Saturation
3. Negative resistance
4. None of the above

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15. Between the peak point and the valley point of UJT emitter characteristics we have __________ region

1. Saturation
2. Negative resistance
3. Cut-off
4. None of the above

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16. In a UJT, the p-type emitter is __________ doped

1. Lightly
2. Heavily
3. Moderately
4. None of the above

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17. Power electronics essentially deals with control of a.c. power at __________

1. Frequencies above 20 kHz
2. Frequencies above 1000 kHz
3. Frequencies less than 10 Hz
4. 50 Hz frequency

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18. The device that does not have the gate terminal is __________

1. Triac
2. FET
3. SCR
4. Diac

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19. The device that exhibits negative resistance region is __________

1. Diac
2. Triac
3. Transistor
4. UJT

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20. The normal way to turn on a diac is by __________

1. Gate current
2. Gate voltage
3. Breakover voltage
4. None of the above

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