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?
What will be an ideal response?
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.
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Hard hats are required only for construction jobs that have been determined to have excessive hazards.
Answer the following statement true (T) or false (F)
?What happens if the standoff distance is increased?
A. ?The arc force is increased because the resistance is higher and the voltage increases. B. ?The plasma are will begin to drift sideways due to arc blow. C. ?The plasma stream will lose some of its stiffness. D. ?Not much until the distance is so great that the arc goes out.
A visual inspection of the metering valve includes ________
A) Verifying that the valve stem moves when the brakes are applied B) Inspection for excessive leakage C) Both A and B D) Neither A nor B
Unlike magnetic poles ________ and like poles ________
A) attract, repel B) repel, repel C) repel, attract D) attract, attract