The frequency of the electromagnetic waves in a microwave oven is 2.2 GHz.
A large piece of cake is placed inside this microwave oven without the rotating plate, and left to cook for a while.
Once the cake is cut, the distance between adjacent uncooked points is closest to ...
..a half wavelength. Compute the wavelength from the speed lf light and the frequency.
There are uncooked points because of standing (micro)waves inside the oven enclosure.