Dangerous radiation from looking into your microwave oven?
Even though you can see into the microwave oven when your food is cooking, the microwaves are effectively blocked from getting out into the room because the holes in the metal screen on the microwave oven door are about 1 mm in diameter compared to a 120 mm wavelength for the microwaves. The wavelength of the microwaves is about 120 times the size of the holes, and can't "see" the holes to get out. This is an application of the fact that you cannot image anything that is smaller than the wavelength of the radiation you use to image it. You can see through the holes because at 500 nm wavelength, the visible light wavelengths are about 2000 times smaller than the holes.