I'm rather new to the electrical space and Im starting out by trying to complete basic circuits in order to make sure I understand how all of the components work. After completing some basic labs with a 5v power source, an LED, and some resistors I decided to try replacing the resistors with a potentiometer. It's my understanding that by using terminals 1 and 2, you can turn the pot into a rheostat or adjustable resistor. So I put the pot in place of the resistor and sure enough, I could make the LED dim and brighten by adjusting the position of the knob on the pot. I also hooked up my multimeter in parallel to the LED and saw the voltage increase and decrease with the LED. This all made sense to me and was how I thought things should work. However, I then unplugged the LED from the breadboard just leaving the multimeter leads attached to the circuit. The reading returned immediately to 5v and stayed there regardless of where the pot was set. So now Im a little confused. Why would my multimeter only register a change in voltage when the LED was in parallel? Shouldnt the multimeter still be registering the changes in voltage based on where the pot is set?
I've found that if I configure the pot using all 3 terminals then it works as expected and I see the voltage changing on the multimeter even without the LED. In that configuration Im using terminal 1 as ground, 2 as output, and 3 as input. Im still confused why the initial experiment with using the pot as a rheostat with only two terminals wont register voltage change on my multimeter though.