Question 1

If a variable resistor is used to control the gate of the triac, the same control problems exist as did with the SCR.

Accepted Answer

A variable resistor controlling the gate of a triac can face similar issues as with an SCR, such as non-linear control and sensitivity to gate current variations.

Question 2

If a diode is connected in series with the gate, it permits ____ of the AC cycle to provide gate current.

Accepted Answer

When a diode is connected in series with the gate of a device, it rectifies the AC signal, allowing only one half of the AC cycle to pass through and provide gate current. This is because a diode conducts current in one direction only.

Question 3

If a triac is used as the controlling element for a motor, the thermostat cannot furnish the amount of gate current necessary to control the triac.

Accepted Answer

A thermostat can be designed or integrated with a circuit to provide the necessary gate current to control a triac, thus it can indeed furnish the amount of gate current required for controlling the triac in a motor control application.

Question 4

The triac is made like two SCRs connected in parallel facing in opposite directions with their ____ tied together.

Accepted Answer

The triac is essentially composed of two silicon-controlled rectifiers (SCRs) connected in parallel but oriented in opposite directions, with their gate leads tied together to control the flow of current in both directions.

Question 5

By reversing the ____ of the ohmmeter, both of the SCRs in a triac can be tested.

Accepted Answer

By reversing the polarity of the ohmmeter, both of the SCRs (Silicon Controlled Rectifiers) in a triac can be tested, as a triac is a bidirectional device.

Question 6

The triac cannot be tested with an ohmmeter.

Accepted Answer

A triac can be tested with an ohmmeter by checking the resistance between its terminals in different configurations to determine if it switches properly.

Question 7

The triac is a device very similar in operation to the SCR.

Accepted Answer

Both the triac and the SCR (Silicon Controlled Rectifier) are semiconductor devices used for controlling current flow. However, while the SCR can control current in only one direction, the triac can control it in both directions, making it effectively a bidirectional SCR.

Question 8

The schematic symbol for the triac is similar to the connection of the two ____.

Accepted Answer

The schematic symbol for a triac resembles the connection of two Silicon Controlled Rectifiers (SCRs) in antiparallel, allowing it to conduct current in both directions when triggered.

Question 9

When an SCR is connected into an AC circuit, the output voltage is rectified to direct current.

Accepted Answer

An SCR (Silicon Controlled Rectifier) is a semiconductor device that allows current to flow in only one direction, effectively rectifying AC (Alternating Current) to DC (Direct Current).

Question 10

In the accompanying figure, the triac can control a _____ amount of load current with a small amount of gate current.

Accepted Answer

The answer of In the accompanying figure, the triac can...

Quiz 24: The Triac