Answer:
A voltage-controlled resistor (VCR) is a three-terminal active device with one input port and two output ports. The input-port voltage controls the value of the resistor between the output ports. VCRs are most often built with field-effect transistors (FETs). Two types of FETs are often used: the JFET and the MOSFET.
Info from Wikipedia :)
hope this helps :D
Answer: Yep! I made a yt vid on them so look this up:
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NEVER GOING TO GIVE YOU UP
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I believe the answer is A. hope this helps :)
<h2>
Answer:When electrons absorb or emit quantized units of energy in the form of photons.</h2>
Explanation:
When a electron is collided with a photon with exactly the same energy it would require to get to any of the farther orbits,electron transition takes place to an orbit depending on the energy of the photon.
When electrons emit exactly the same amount energy that is difference between the current energy level and the new level,then the electron makes a transition to the new level.