Lamp dimmers

I recently learned that there are multiple ways to wire a potentiometer, as a voltage divider (left) or as a variable resistor (right two setups). I'm a beginner, so I'm not sure which is more appropriate in different situations. As a light dimmer they seem pretty comparable - you get a bit more current through the lamp when wired as a variable resistor at the same wiper position. In this sort of circuit are there any advantages of one setup vs the other (e.g. is one drawing more power)? And as a variable resistor, I've sometimes seen the second and third posts connected (right top). Is there any reason to do this?

published 4 years ago