Some magnetrons have ceramic insulators with beryllium oxide (beryllia) added. The beryllium in such oxides is a serious chemical hazard if crushed then inhaled or ingested. In addition, beryllia is listed as a confirmed human carcinogen by the IARC;[citation needed] therefore, broken ceramic insulators or magnetrons should not be handled. This is a danger if the microwave oven becomes physically damaged, if the insulator cracks, or when the magnetron is opened and handled, yet not during normal usage.
Some magnetrons have ceramic insulators with beryllium oxide (beryllia) added. The beryllium in such oxides is a serious chemical hazard if crushed then inhaled or ingested. In addition, beryllia is listed as a confirmed human carcinogen by the IARC;[citation needed] therefore, broken ceramic insulators or magnetrons should not be handled. This is a danger if the microwave oven becomes physically damaged, if the insulator cracks, or when the magnetron is opened and handled, yet not during normal usage.
The Toshiba EM925A5A-BS cooked the most evenly in our tests and was one of the few models we found with an option to mute the sound. The Toshiba has a control panel that’s very easy to use and includes express cooking options and preset cooking functions for specific tasks like making popcorn or cooking a potato. Also, the Toshiba is one of the few models we tested with a handle for opening the door (versus a push-button release), which some people may prefer.

We looked for small microwaves around 0.5 cubic foot and midrange models between 0.9 and 1.6 cubic foot. Unless you really need a turntable big enough to spin a 13-by-9-inch casserole dish or two small plates, we found that models over 1.6 cubic foot had too big a footprint for most spaces. Most people use microwaves for reheating leftovers, so there’s no reason to have an oven cavity that’s large enough to fit a 20-pound turkey. That said, you’ll want to measure the diameter of your dinner plates before getting a microwave to be sure they’ll fit.


Fast cooking was our top priority — if a microwave can’t prepare a meal speedily, it isn’t the best. Ray Boxman, Professor Emeritus of Electrical and Electronics Engineering at Tel Aviv University, told us microwaves cook fast “because the microwave energy penetrates into the food, in contrast to conventional heating, which only delivers heat to the surface of the food, and a lot of time is needed for the heat to diffuse inward.”
Closed containers, such as eggs, can explode when heated in a microwave oven due to the increased pressure from steam. Intact fresh egg yolks outside the shell will also explode, as a result of superheating. Insulating plastic foams of all types generally contain closed air pockets, and are generally not recommended for use in a microwave, as the air pockets explode and the foam (which can be toxic if consumed) may melt. Not all plastics are microwave-safe, and some plastics absorb microwaves to the point that they may become dangerously hot.
All microwaves use this same core technology, but today, there are many models available that come with a variety of additional features. For instance, many products have pre-programmed settings to cook common foods, as well as various cooking methods, such as steaming and grilling. Depending on what size and features you want, you can spend anywhere from $20 to $2,000 on a new microwave. 
Every microwave oven contains a magnetron, which generates microwaves. Those waves are then guided into the oven’s cavity, where they bounce around, rapidly swinging the polarity of charged molecules in foods (particularly water, fats, and sugars) and generating heat. Metal mesh on the door keeps those large-wavelength microwaves from escaping the metal box and cooking you. (This great video uses a disassembled model to explain further.)
^ Gallawa, J Carlton (1989). "A Brief History of the Microwave Oven". The complete microwave oven service handbook : operation, maintenance, troubleshooting, and repair. Englewood Cliffs, N.J.: Prentice Hall. ISBN 9780131620179. OCLC 18559256. Retrieved 11 October 2017. Chapter link is hosted at the Southwest Museum of Engineering, Communication and Computation; Glendale, Arizona.

Like the 0.9-cubic-foot model, this Toshiba has one-touch start buttons from 1 to 6 minutes, a plus-30-seconds button, and a child-lock function. This model also shares several other features with the smaller Toshiba, such as a memory function and a multistage cooking function—but, realistically, we don’t think most people will use these controls often.
^ Gallawa, J Carlton (1989). "A Brief History of the Microwave Oven". The complete microwave oven service handbook : operation, maintenance, troubleshooting, and repair. Englewood Cliffs, N.J.: Prentice Hall. ISBN 9780131620179. OCLC 18559256. Retrieved 11 October 2017. Chapter link is hosted at the Southwest Museum of Engineering, Communication and Computation; Glendale, Arizona.
What is a microwave ovens role in your home? Do you need the best compact microwave to fit on a tiny counter and travel with you when you switch apartments? Do you need the best built in microwave that works with your oven range? No matter your kitchen appliance situation, if you’re stuck with a clunky, ugly microwave, it’s time to improve your cooking situation.
The Toshiba EM925A5A-BS cooked the most evenly in our tests and was one of the few models we found with an option to mute the sound. The Toshiba has a control panel that’s very easy to use and includes express cooking options and preset cooking functions for specific tasks like making popcorn or cooking a potato. Also, the Toshiba is one of the few models we tested with a handle for opening the door (versus a push-button release), which some people may prefer.
The Quick Touch is a little expensive at $250. Amazon reviews also warn that the words printed on the buttons can wear off after years of use … but we actually liked the implication that this microwave will last long enough for some surface-level wear. If you’re going to pay more for an appliance it should be long-lasting and awe you with its usability and features — the Quick Touch did that for us.
Direct microwave exposure is not generally possible, as microwaves emitted by the source in a microwave oven are confined in the oven by the material out of which the oven is constructed. Furthermore, ovens are equipped with redundant safety interlocks, which remove power from the magnetron if the door is opened. This safety mechanism is required by United States federal regulations.[60] Tests have shown confinement of the microwaves in commercially available ovens to be so nearly universal as to make routine testing unnecessary.[61] According to the United States Food and Drug Administration's Center for Devices and Radiological Health, a U.S. Federal Standard limits the amount of microwaves that can leak from an oven throughout its lifetime to 5 milliwatts of microwave radiation per square centimeter at approximately 5 cm (2 in) from the surface of the oven.[62] This is far below the exposure level currently considered to be harmful to human health.[63]
Consumer ovens work around a nominal 2.45 gigahertz (GHz) — a wavelength of 12.2 centimetres (4.80 in) in the 2.4 GHz to 2.5 GHz ISM band— while large industrial/commercial ovens often use 915 megahertz (MHz) — 32.8 centimetres (12.9 in).[26] Water, fat, and other substances in the food absorb energy from the microwaves in a process called dielectric heating. Many molecules (such as those of water) are electric dipoles, meaning that they have a partial positive charge at one end and a partial negative charge at the other, and therefore rotate as they try to align themselves with the alternating electric field of the microwaves. Rotating molecules hit other molecules and put them into motion, thus dispersing energy. This energy, dispersed as molecular rotations, vibrations and/or translations in solids and liquids raises the temperature of the food, in a process similar to heat transfer by contact with a hotter body.[27] It is a common misconception that microwave ovens heat food by operating at a special resonance of water molecules in the food. As noted microwave ovens can operate at many frequencies.[28][29]
Ever wondered how microwaves heat up food so quickly and efficiently? These appliances contain a part called a magnetron, which uses electricity to create high-powered radio waves. The waves are pushed into the microwave’s interior, where they bounce off the metal walls and penetrate whatever food you’re cooking. The turntable spins to help the waves hit the food from all angles, and this process makes the molecules in the food vibrate, warming them up. However, one of the downsides of microwave cooking is that radio waves can only travel a few centimeters into your food, so larger items don’t always cook evenly.
The exploitation of high-frequency radio waves for heating substances was made possible by the development of vacuum tube radio transmitters around 1920. By 1930 the application of short waves to heat human tissue had developed into the medical therapy of diathermy. At the 1933 Chicago World's Fair, Westinghouse demonstrated the cooking of foods between two metal plates attached to a 10 kW, 60 MHz shortwave transmitter.[3] The Westinghouse team, led by I. F. Mouromtseff, found that foods like steaks and potatoes could be cooked in minutes.
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