Microwave ovens are indeed made of metal, but they are specifically designed and constructed to prevent arcing and other safety hazards associated with metal objects in the cooking chamber. Here are a few key design features that allow microwave ovens to be made of metal without causing arcing:
Interior Coating: The interior of the microwave oven chamber is typically lined with a special coating known as a microwave-absorbent material. This material is designed to prevent reflections and absorb the microwaves rather than reflecting them. The coating helps to minimize the chances of arcing by preventing the microwaves from interacting with the metal surface of the oven.
Waveguide and Sealing: The waveguide, which directs the microwaves from the magnetron to the cooking chamber, is carefully designed and sealed to ensure that the microwaves remain contained within the designated path. This prevents them from escaping into the metal casing of the microwave and causing arcing.
Door Design: The microwave door is constructed with a metal mesh or grid pattern. This pattern allows you to see through the door while also serving as a barrier for the microwaves. The holes in the mesh are smaller than the wavelength of the microwaves, preventing them from leaking out while still allowing you to observe the cooking process.
It's worth noting that while microwave ovens are designed to prevent arcing, it is crucial to follow safety guidelines and avoid placing metal objects, especially those with sharp edges or points, inside the cooking chamber. Metal objects can cause arcing, spark discharge, and potentially damage the oven or create a fire hazard.
In summary, microwave ovens are constructed with materials and design features that prevent arcing. The interior coating, waveguide sealing, and door design all work together to contain the microwaves and ensure safe operation while allowing the oven to be made of metal.