Power Electronics

21. The triac is __________

1. Like a bidirectional SCR
2. A four-terminal device
3. Not a thyristor
4. Answers (1) and (2)

View answer

22. The UJT may be used as __________

1. Am amplifier
2. A sawtooth generator
3. A rectifier
4. None of the above

View answer

23. The V-I characteristics for a triac in the first and third quadrants are essentially identical to those of __________ in its first quadrant

1. Transistor
2. SCR
3. UJT
4. none of the above

View answer

24. To turn on UJT, the forward bias on the emitter diode should be __________ the peak point voltage

1. Less than
2. Equal to
3. More than
4. None of the above

View answer

25. When a UJT is turned ON, the resistance between emitter terminal and lower base terminal __________

1. Remains the same
2. Is decreased
3. Is increased
4. None of the above

View answer

26. When the emitter terminal of a UJT is open, the resistance between the base terminal is generally __________

1. High
2. Low
3. Extremely low
4. None of the above

View answer

27. When the temperature increases, the inter-base resistance (RBB) of a UJT __________

1. Increases
2. Decreases
3. Remains the same
4. None of the above

View answer

28. When the temperature increases, the intrinsic stand off ratio __________

1. Increases
2. Decreases
3. Essentially remains the same
4. None of the above

View answer

29. Which of the following is not a characteristic of UJT?

1. Intrinsic stand off ratio
2. Negative resistance
3. Peak-point voltage
4. Bilateral conduction

View answer