[emmelaich]

You'd think grapes would make a poor resonant cavity too. But you can create plasma with grapes in a microwave oven.

[CamperBob2]

Yes, and that's precisely because they are so lossy. It's not a resonant effect. You're just taking advantage of the grape's cross section being roughly a quarter-wavelength at 2.4 GHz, which allows the magnetron to dump a ton of power into it.

It's analogous to using a couple of forks to operate a pickle from 120V.

[MacsHeadroom]

>roughly a quarter length

Is that not resonance?

[CamperBob2]

The same thing would happen with an ideal resistor whose leads formed a dipole of the right length, so no.

[the_only_law]

Before I act like an idiot and go do this, is there any significant safety risk or major risk to the equipment in doing this?

[CamperBob2]

Should be fine as long as you put a cup of water in the microwave alongside the grape. They aren't really meant to run empty, and microwaving a single grape would be basically running it empty.