This was an enjoyable couple of minutes, and I look forward to more levels! The last two levels had the "Aha!" moment that makes a great puzzle.
There is one oddity with the controls. Playing with a mouse and keyboard, if I held down the change polarity key long enough, releasing the key changed the polarity again. This resulted in a couple of cases where I would change the polarity, then it would change back again and I would have to press the key again.