I have an incredibly cool experiment for you to try. Take a grape, slice it almost all the way in half and open it up so you have two hemispheres of grape connected by a thin strip of skin. Now, put it on a plate in the microwave and zap it for 10 seconds or so.
(Seriously, try it right now.)
The microwaves have a wavelength of about 12.5 cm so the grape sections are about a quarter wavelength long. My explanation for the grape catching on fire (really, go try it) is that each of the grape halves is sampling a different part of the electric field so you set up a large potential between the halves until the central skin finally burns through.
Does this make sense?