Today I decided to start on Experiment #4 (Variable Resistance). For this experiment, we the book introuduced a new equipment called the potentiometer. A potentiometer can control the current and vary the resistance of the circuit.
However, when you used a multimeter to measure while spinning the disk around the numbers would change dramatically.
I think that potentiometers are used for dimming the lights. You probably have one on your light switch. It is either a disk or a bar that goes up and down.