WHY DOES METAL REACT SO VIOLENTLY IN A MICROWAVE?

Tom Boon

Microwaves are a kind of electromagnetic wave, and as such can create electric currents in metals. Many of the microwaves are actually reflected by the metal and can reflect back onto the magnetron – the part of the oven that produces the microwaves, which can overheat and become damaged. When microwaves hit metal surfaces, free electrons in the metal start to move around; the movement of this charge is how an electric current arises. Some of these electrons will move too much and will actually jump from the metal to the air, which becomes temporarily ionised. This can result in a phenomenon called ‘arcing’ where an electric spark is produced. Thin metal produces more resistance to an electric current than thick metal, and so can become very hot, even melting.