You might be wondering what I’m doing here.
Have you ever experimented with your microwave before, or had it reacted violently to an item you had put in? There are many things that behave this way—a notable example is grapes, which can explode when microwaved. However, how exactly do microwaves heat food, and why can they have such strange effects? More importantly, what are some other fun things we can put into them?
Microwaves differ from conventional ovens in that they emit microwaves to vibrate water molecules in your food, generating heat. Similar to light, these waves are electromagnetic, but with longer wavelengths than X-rays; thus, contrary to popular belief, they are not radioactive. While they can still be harmful if leaked, modern microwaves seal them inside during the cooking process. One side effect of this process is that it heats foods with large amounts of water more quickly, which plays a large part in the microwave’s strange effects on water-rich grapes.
There’s a reason why grapes heat up so quickly. Initially, many people assumed that the grapes had to be prepared in a very specific way: cut cleanly down the middle, with a small strip of skin connecting the two halves. A widespread explanation for this was that the explosion was caused by conduction through the skin. Despite this, the phenomenon also occurs with two different, uncut grapes placed next to each other, which has long puzzled scientists. In the end, a different conclusion was reached, where the grapes trap microwaves from the oven, which resonate inside, creating spots of heat in the space between. However, grapes aren’t the only objects that act this way.
Many other objects also react violently due to the unusual properties of microwaves. For instance, microwaving water for too long in a smooth, clean cup can result in superheated water. While it may not appear to be boiling, it can violently explode out of its cup when slightly disturbed—causing severe burns.
Metals placed in microwaves can also cause significant damage. Microwave walls are made of metal, and bounce waves off each other toward the food. However, placing a metal object inside can reflect the waves irregularly, damaging the microwave. Besides this, metal in a microwave occasionally becomes extremely hot and will incinerate food touching it if left for too long. It can also create an electric field at the ends or edges of pieces of metal, resulting in sparks and a popping sound.
Finally, microwaving nothing has many similarities to using metal; notably, the microwaves that are normally absorbed by food have nothing to heat up—damaging the inside of the microwave. Running microwaves with nothing inside for a few seconds may be inconsequential. But look out, explosions are still possible if left for too long!
Microwaving food is one of the most interesting methods of heating and can put on quite the show. However, these reactions are often very damaging, and they run the risk of breaking your microwave or even causing life-threatening injuries. While explosions are definitely fun, we should probably think twice before attempting to trigger them.
References:
https://www.wired.com/story/why-a-grape-turns-into-a-fireball-in-a-microwave/ https://www.tastingtable.com/733460/what-really-happens-when-you-microwave-nothing/