Figure 20-05

-The circuit in the accompanying figure shows a phototransistor used to turn on a relay coil. What is the difference when the phototransistor is in the presence of darkness versus light?

Question

Figure 20-05
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-The circuit in the accompanying figure shows a phototransistor used to turn on a relay coil. What is the difference when the phototransistor is in the presence of darkness versus light?

Quizplus · Accepted Answer

The Answer is When the phototransistor is in darkness, no electrons are emitted by the base junction, and the transistor is turned off. When the phototransistor is in the presence of light, it turns on and permits current to flow through the relay coil.

Figure 20-05 ​

Figure 20-05