One might wonder why it only happens with metal objects. There is a perfectly scientific reason behind it. According to The School of Engineering at MIT, microwaves are a form of electromagnetic radiation that is generated by a device called magnetron. The job of these waves is to pulse back and forth rapidly inside an oven at a carefully calibrated frequency. These waves pass through plastic, paper and glass and are absorbed by the food. When the food absorbs the waves, the molecules oscillate back and forth, which then creates heat and cooks the food from the inside out.
These waves cannot pass through metal. When the radiation hits the metal, the metal bounces back the waves to the walls of the microwave. The waves jump around erratically, and can possibly damage the inside of the microwave.
Metal is actually so good at reflecting radiation, that the window that’s on the door of the microwave, actually contains metallic mesh. The radiation that hits the window is bounced back, making it impossible for radiation to escape the microwave.
According to Physics.org, metals are a lot more solid than food. So instead of absorbing the electromagnetic waves, some metals either deflect the waves, or heat up really quickly. As the metals become extremely hot and in such quick time, it then causes the metal to either spark or burn. Although putting metal inside of a microwave may not set your house on fire, it still isn’t a good idea to attempt to do so. Not only will it give you more than a good scare, but you will also have to replace your microwave.
