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.
Where can I buy a replacement microwave door?
You can typically purchase a replacement microwave door assembly from the appliance manufacturer's authorized parts distributors or through online appliance parts retailers. You will need to know the make and model number of your microwave to ensure you order the correct, compatible door. Some universal microwave door parts might be available, but it's best to get an exact match for safety and performance. Check the manufacturer's website or contact their customer support for guidance on ordering replacement parts.