A resistor is essentially a poor conductor of electricity. When you send current through a resistor, that current always experiences a voltage drop, never a voltage rise. One way to understand this effect is that
A) more current leaves a resistor than enters it, so the voltage must go down to compensate.
B) it is easy to turn electric energy into thermal energy but not the other way around.
C) less current leaves a resistor than enters it, so the voltage must go down as well.
D) current can only flow forward through a resistor, never backward.

Question

Quizplus · Accepted Answer

Resistors convert electrical energy into thermal energy, which is a one-way process. This conversion causes a voltage drop across the resistor as electrical energy is dissipated as heat, not because of a change in the amount of current or its direction.

A Resistor Is Essentially a Poor Conductor of Electricity