As a kid, my dad would always encourage me to try strange science experiments in order to pique my interest in the natural sciences. One day, he had purchased a new microwave, and was getting rid of the old one. He decided it would be fun to show me what happens to a CD when you put it in the microwave. My dad is a pretty cool dad, but before we go any further, a disclaimer:

DO NOT MICROWAVE CDS. If you choose to ignore this warning, remember that I WARNED YOU NOT TO DO THIS. IT’S DANGEROUS. At best, you’ll end up with a broken microwave. Worse yet, there will be TOXIC FUMES FLOATING AROUND YOUR HOUSE. WORST OF ALL YOU MIGHT START A HOUSE FIRE DO NOT ACTUALLY CONDUCT THIS EXPERIMENT.

Okay, now that that boring disclaimer stuff is out of the way, here’s what happens when you microwave a CD! In short, the CD is totally ruined, and you get a light show in your microwave; arcs of electricity that look a lot like lightning pulse throughout the microwave; all of this happens in as little as 3 seconds. It really is a sight to behold, and one worth looking up a YouTube video of. With what happens out of the way, you might ask why it happens.

Microwaves (the appliance) produce microwaves (an electromagnetic wave). In their normal application, microwaves are handy because they pass through some materials, like glass, without affecting them, but they create rapid vibration in other materials. These rapid vibrations produce heat as a byproduct, and that heat warms your food. When microwaves touch certain metals, however, an entirely different effect takes place.

Metals can, ostensibly, be put into a microwave. In fact, in order to stop microwaves from reaching your skin, your microwave is actually lined with sheet metal, creating what’s known as a Faraday cage. While we won’t go into Faraday cages too much here, know that they can block electromagnetic waves from entering or leaving a place. When there isn’t an even coating of metal, however, is when problems form. The aluminum in a CD will be vaporized by the microwaves; that vapor is an excellent conductor of electricity, and an electrical field will form. That electricity will then arc to other aluminum in the CD, which will vaporize; this will continue until all the aluminum has been vaporized.

That’s why this experiment is not the best to try at home; you get a lot of aluminum vapor in your microwave, and quite a light show! If your microwave is giving off sparks without a CD inside, it’s probably time to call an electrician. Our team of qualified electricians in Winnipeg can handle all kinds of electrical problems, so if you have a short circuit, give us a call!