Title: Thyristor Test
Course: Electronics Theory (IC 102-IC 102) > Section: Assessments

Q: The term thyristor includes all the semiconductor devices which show inherent on-off behavior, as opposed to allowing gradual changes in conduction.
- True
- False
A: True

Q: A UJT has more than one PN junction.
- True
- False
A: False

Q: Besides the positive gate potential required to fire the SCR, the cathode must be more positive than the anode to turn on.
- True
- False
A: False

Q: The SCR is an unidirectional device.
- True
- False
A: True

Q: The triac is connected in series with the load.
- True
- False
A: True

Q: An IGBT combines the characteristics of a bipolar transistor and a MOSFET.
- True
- False
A: True

Q: Once triggered, the gate of the __________ loses control of the current flow and it will keep conducting.
- triac
- SCR
- both A and B
A: triac

Q: The triac turns off when __________.
- the voltage is removed from the gate
- the amperage flowing through the triac falls below the holding current value
A: the voltage is removed from the gate

Q: The triac will be triggered into conduction when the voltage on __________.
- its T2 terminal is positive and the gate is positive
- its T2 terminal is positive and the gate is negative
- its T2 terminal is negative and the gate is positive
- its T2 terminal is negative and the gate is negative
- all of the above
A: its T2 terminal is positive and the gate is positive

Q: To conduct, the SCR must have the __________.
- anode more positive than the cathode
- cathode more negative than the anode
- gate more positive than the cathode
- all of the above
A: anode more positive than the cathode

Q: The SCR turns off by __________.
- reducing the holding current value
- removing the positive potential at the gate
- both A and B
A: reducing the holding current value

Q: Once triggered on, the SCR (with the cathode connected to common) will conduct for the remainder of a(n) __________.
- AC cycle
- negative alternation
- positive alternation
A: AC cycle

Q: When testing an SCR with an ohmmeter and placing the positive lead on the anode and the negative lead on the cathode, the meter should indicate __________.
- high resistance
- low resistance
- short circuit
- none of the above
A: high resistance

Q: If the meter was connected as in problem 10 and the gate lead was briefly shorted to the anode, the meter would indicate __________.
- the same
- a large resistance
- a small resistance
- briefly a low resistance and then a very large resistance (Assume the meter can provide a holding current.)
A: the same

Q: For a triac to conduct for one complete cycle of a sine wave, __________.
- the gate must be pulsed once at 0 degrees
- the gate must be pulsed at 0 degrees and at 180 degrees
- the gate must be pulsed at 0 degrees and at 270 degrees
- none of the above
A: the gate must be pulsed once at 0 degrees

Q: A diac is used to trigger __________.
- an SCR
- a UJT
- a triac
A: an SCR

Q: The diac is a __________device.
- unidirectional
- bidirectional
A: unidirectional

Q: To turn off an IGBT, a __________ voltage is applied to the gate.
- negative
- positive
- either A or B
A: negative

Q: The diac operates similar to two zener diodes placed back-to-back in series.
- True
- False
A: True

Q: The diac can be tested with an ohmmeter to determine if it is operating properly.
- True
- False
A: False