What Happens If You Start The Microwave Oven With Nothing Inside
You probably know you shouldn't microwave aluminum foil, since it sparks, and you don't want to microwave a whole egg, lest it blows up, but what about microwaving nothing? That surely isn't bad, right? What's going to happen? It turns out that running your microwave while empty (which is most likely to happen by accident, when you forget to pop whatever it is you want to cook actually into the microwave) can be quite dangerous.
According to the manufacturer of Sub-Zero and Wolf, microwaving nothing could simply result in damaging your microwave even if it doesn't implode from the waves of energy it uses to heat and cook food. And if you are lucky enough to own a microwave made by one of their top-quality brands, then you probably want to take care of it. No one wants to have to replace a perfectly good appliance or pay for repairs when the problem could have been avoided. And that's exactly what you'll have to do if the waves do cause damage to the small appliance.
As noted previously, the water molecules in frozen foods are notall bound up perfectly inside ice crystals. As long as there are a fewrelatively mobile water molecules, even frozen food will eventually absorbenough energy to melt. Once that happens, the food can cook easily. Ofcourse, the melting process is frequently very non-uniform so that foodcomes out with hot and cold regions. In general, frozen food cooked ina microwave is not very satisfying.
As the microwaves bounce around the inside of the cooking chamber,they tend to interfere with one another. There are usually regions in whichthe waves that follow various paths almost cancel one another and regionsin which the waves reinforce one another. These regions do not cook foodequally well. If the microwaves are canceled in one region, cooking willbe slow there. If the microwaves reinforce one another in another region,cooking will be fast there. If you simply leave food in one place and tryto cook it in the microwaves, the cooking will be uneven. However, if thefood is rotated continuously, these good and bad cooking regions will beblurred away so that the food will all cook at about the same speed.
I've already noted the issues of warming frozen food. However, the"defrost" setting is an interesting issue. If you've ever watcheda microwave trying to defrost food, you've probably noticed that it heatsthe food briefly and then waits. It repeats this process many times. Whatit is doing is depositing energy (via the microwaves) into whatever watermolecules are able to absorb microwaves. It then waits for this energyto flow as heat into the nearby food. Once the heat has been distributedrather evenly, the oven adds some more energy by turning the magnetronback on. This cycle of heating and waiting allows the food to defrost fairlyevenly. Still, microwaves are likely to create hot and cold regions inthe food so that some parts of the food will cook rather than defrost whilesome parts remain frozen.
I'm not sure what wire you are referring to. Most microwaves containno wires in their cooking chambers because any wire inside will tend toreflect the microwaves. The exception is temperature probes, which allowthe oven to monitor the food's internal temperature. Such a probe doesupset the microwave fields around it and will probably have some effecton the cooking taking place around it.
A microwave oven heats food by depositing energy in its water. Ifyou cook the food long enough, that water can begin to boil. If the foodhas a hard outer shell (e.g. a potato or a corn kernel), the boiling watercan create enough pressure in the food to make it explode. That is whatpop's the corn in microwave pop-corn and why the potato explodes if youdon't pierce it so that steam can escape.
When you put solid food (a potato, not soup) into a conventionaloven, the heat flows slowly into the center of that food. This heat mustwork its way into the food via thermal conduction, in which adjacent atomsand molecules transfer their motional energies in a long bucket-brigadeprocess. The last part of a potato to become hot is its center. However,in a microwave oven, the microwaves travel well into the solid food anddeposit their energy everywhere. The potato cooks throughout at a relativelyeven rate. The actual amount of heat and energy involved in conventionaland microwave cooking is about the same. However, the microwaves can heatthe food throughout without having to wait for the slow process of conductionto carry it inward from the food's surface.
The cooking chamber of a microwave oven is always metallic. Eventhe glass door has a metal grid across it to keep the microwaves inside.This metal chamber may be coated with paint or plastic but it is therenonetheless. Without it, the microwaves would leak out and the oven wouldbe hazardous and inefficient. It would cook objects throughout the kitchen.
The microwave oven has a transformer that steps up the supply voltage to 4,000 volts and feeds it to the magnetron. Within the magnetron is a filament that heats up pretty quickly and starts releasing electrons.
Some protective devices inside the microwave oven shield the magnetron from the waves bouncing back from the cooking chamber. Additionally, the cavity, the door, and the tray absorb the excess energy while cooking your food.
You are actually exposed to less radiation if you stick your hand in a properly functioning microwave oven right after it turns off. First of all, the microwaves emitted by a microwave oven are not harmful beyond their ability to heat you. Microwaves are non-ionizing, meaning that they do not have enough energy per photon to rip electrons off of atoms or break chemical bonds, which is what leads to cancer and radiation sickness. In fact, microwaves have far less energy per photon than the light from a candle or even the infrared thermal radiation from your hand. Microwave ovens emit electromagnetic waves in the frequency range of gigahertz (GHz). These are the same types of waves used by radars, cell phones, and WIFI routers. Microwaves can burn you if they are powerful enough and hitting you for long enough, but this is fundamentally no different from being burned by a campfire's thermal radiation. Sticking your hand in the microwave while it is on (which would require breaking the oven's safety features) and leaving it there is a bad idea because you will get burned.
Also, a properly functioning microwave oven automatically turns off the moment you open the door. The last bit of microwaves emitted by the oven bounce around inside and are absorbed within microseconds, long before you have even finished opening the door. By the time you stick your hand in the oven, the last bits of microwaves are long gone. Microwaves are a form of electromagnetic waves, just like visible light. The microwaves in the oven disappear when the door opens just as quickly as a room gets dark when you turn off the light.
The walls of a microwave oven are metal, which keep microwaves inside from leaking out. The oven is constructed to avoid leaking microwaves not because they cause cancer, but because that would be a waste of energy. The oven's job is to cook food; a job it would not do very well if its energy were leaking out into the room. Interestingly, the metal walls of a microwave oven also block a lot of external radiation (from the sun, stars, rocks, storms, etc.) from getting in. Because of this shielding effect, your hand inside a non-running microwave actually receives less radiation than your hand out in the open air. Either way, the radiation you are exposed to is so low-energy that there is nothing to be concerned about.
Thamer FA, Al-Wakeel HB, Mohammadridha T, Ibraheem ZT. An overview on a technique to measure and control of the elctromagnetic radiation inside a microwave oven. IJCCCE. 2021;21(1):38-52. doi:10.33103/uot.ijccce.21.1.4
When a microwave operates with no food inserted, the radioactive waves will continue to bounce around aimlessly in the oven, looking for something to latch onto. This energy will continue to bounce around indefinitely until the timer runs out.
It would be easy to assume that, because certain items are unsafe in microwaves, it must be safe to operate a microwave with nothing inside of it. However, this is definitely not the case, and could well prove to be one of the most harmful things you could do to your microwave.
Yes. There is definitely a risk of a fire developing if you operate a microwave with nothing in it. This would be caused by the radioactive waves damaging the internal mechanisms and causing the microwave to overheat.
The most common cause of smoke is food bits burning on the heating element or on the bottom of the stove. A good cleaning is in order, which starts by using your oven's self-cleaning mode. In a story about removing bad smells from your oven, we mentioned that self-cleaning mode should be used with a lot of discretion. Follow this guide to cleaning your oven.
If you don't clean with vinegar or use a self-cleaning mode, your cleaning method may be the problem. Store-bought oven cleaners tend to smoke if you don't remove all of the residue from inside your oven after cleaning. Give the interior a good wipe down with a damp cloth once the oven's cooled. This will prevent smoke the next time you use it.
Although heat is produced directly in the food, microwave ovens do not cook food from the "inside out." When thick foods are cooked, the outer layers are heated and cooked primarily by microwaves while the inside is cooked mainly by the conduction of heat from the hot outer layers.
Microwave cooking can be more energy efficient than conventional cooking because foods cook faster and the energy heats only the food, not the whole oven compartment. Microwave cooking does not reduce the nutritional value of foods any more than conventional cooking. In fact, foods cooked in a microwave oven may keep more of their vitamins and minerals, because microwave ovens can cook more quickly and without adding water. 2b1af7f3a8