Microwave doors block radiation using a metal mesh with holes smaller than the wavelength of microwaves, but larger than visible light waves.
The metal mesh in a microwave door acts as a Faraday cage for microwave radiation. Microwaves have a relatively long wavelength, typically around 12 cm. The holes in the mesh are significantly smaller than this wavelength, preventing the microwaves from passing through and escaping the oven. However, visible light has a much shorter wavelength, on the order of nanometers, allowing it to easily pass through the same holes, which is why you can see inside the microwave.
While microwave doors are designed to contain radiation, it's always wise to ensure your appliance is in good condition and not damaged.
Does a microwave radiation shield door work like a Faraday cage?
Yes, a microwave radiation shield door functions on the same principle as a Faraday cage. A Faraday cage is an enclosure made of conductive material that blocks external electromagnetic fields. In a microwave oven, the metal casing and the perforated metal mesh in the door work together to create a Faraday cage effect. The mesh's holes are smaller than the microwave's wavelength, preventing the microwaves generated inside from escaping, while allowing visible light to pass through.