If you have time, I would suggest that you look at our new breadboard tutorial:http://www.sciencebuddies.org/science-f ... d-tutorial
There are a couple things in there that might help you understand better. Two important points:
- The jumper wire and the potentiometer are
connected through the holes of the breadboard. This is intentional and not
a short circuit. Hole A26 is electrically connected to hole B26 inside the breadboard. The pictures in the sections "What is inside a breadboard?" and "How are the holes connected?" will explain that better.
- While you push the metal pins of the jumper wire and potentiometer down into the breadboard, the parts that remain above the breadboard are plastic. Plastic is an electrical insulator, so even if the parts were bumping into each other, it would not create a short circuit.
However, your intuition that in general circuit parts should not be touching or bumping into each other is good. This can
cause a short circuit when two exposed metal parts touch each other. In this case, you are safe since the exposed parts are plastic.
Hope that helps, please reply if you have more questions.