WorksheetsACEE 6 Quiz 3
Total questions: 12
Worksheet time: 27mins
A diac is a
unidirectional device.
device with three leads.
bidirectional device.
Which of the following is the best suited for controlling power in ac circuits?
the SCR.
the triac.
an ordinary rectifier diode.
Once an SCR is conducting,
its anode to cathode voltage increases substantially.
the only way to turn it off is with a positive gate voltage.
it can never be turned off.
the gate loses all control.
An RC phase-shifting network is used in SCR an triac circuits to
control the conduction angle of the thyristor.
handle some of the load current.
vary the holding current.
Thyristors are used extensively in
small signal amplifiers.
high-power switching applications.
stereo amplifiers.
The diac continues to conduct until its current drops below a
specifi ed value called the
(a)
Why can’t an SCR or triac be used to amplify an ac signal?
Name the three leads of an SCR.
(a)
What happens to the anode current in an SCR when the breakover voltage is reached?
increase sharply
decrease sharply
increase gradually
decrease gradually
The operating mode 3 of a triac is triggered by
positive anode voltage, positive gate voltage
positive anode voltage, negative gate voltage
negative anode voltage, positive gate voltage
negative anode voltage, negative gate voltage
What is the main advantage of a triac versus an SCR?
In the figure, (a) what voltage does the emitter voltage, VE, need to reach to make the UJT conduct?; (b) what is the frequency of the oscillation?
(a)
