Microwaves how do they work

So, we've gotten through the basic science, but we still haven't covered why exactly microwaves work so well to heat food quickly. The microwaves used in a microwave oven are sent out through a type of antenna that channels them into the cooking area of the appliance.

The waves are contained inside of the appliance thanks to the solid metal walls and mesh door. These microwaves are then absorbed by the water molecules inside of the food. The energy from the microwaves causes the water molecules to vibrate rapidly, which heats the food.

In essence, because water molecules easily absorb microwaves , which cause the molecules to start vibrating rapidly, this becomes a mechanism to turn microwave energy into thermal energy. Just like a cam and roller is a mechanical device for converting rotational energy into linear motion, so too are the interactions of microwaves and water molecules a way of converting microwave energy into heat energy. But why are just the water molecules vibrating?

Water molecules are polar, meaning they have a positively charged side and a negatively charged side. Microwaves have a positive crest and a negative crest, just like any wave does. As the microwaves move throughout the inside of the microwave oven, the water molecules will try to align their poles with that of the microwave. Since microwaves move about rapidly inside of the appliance, the water molecules rapidly try to keep aligning themselves with the motion of the waves.

Just how fast is this happening? Microwaves' positive and negative fields are moving at roughly 2. When you combine this effect with the water molecule's reaction, you can start to realize how microwaves cook food so fast and effectively. The last question we need to answer is why there are often dead spots on the inside of microwave ovens.

For example, why is the center of your food often much colder than the edges? This occurs because some of the microwaves end up canceling each other out. Oftentimes, these places of cancelation are localized, meaning some areas of the microwave oven don't get any "heat". In essence, when the peak of one wave hits the valley of another wave, the result is a canceled-out wave.

This is why most microwaves use a rotating dish in order to ensure even cooking. So, that's how microwave ovens work. They are appliances that use magnets to produce electromagnetic radiation at a particular wavelength, which is directed at water molecules in food, causing them to vibrate and heat up rapidly.

Next time you cook something in a microwave, you won't look at it the same way. By subscribing, you agree to our Terms of Use and Privacy Policy. You may unsubscribe at any time. By Trevor English. Follow Us on. Sponsored Stories. John Loeffler. Maia Mulko. The human eye can only detect a small portion of this spectrum called visible light. A radio detects a different portion of the spectrum, and an X-ray machine uses yet another portion.

Visible light, microwaves, and radio frequency RF radiation are forms of non-ionizing radiation. Non-ionizing radiation does not have enough energy to knock electrons out of atoms.

X-rays are a form of ionizing radiation. Exposure to ionizing radiation can alter atoms and molecules and cause damage to cells in organic matter. Microwaves are used to detect speeding cars and to send telephone and television communications. Industry uses microwaves to dry and cure plywood, to cure rubber and resins, to raise bread and doughnuts, and to cook potato chips. But the most common consumer use of microwave energy is in microwave ovens.

Microwaves have three characteristics that allow them to be used in cooking: they are reflected by metal; they pass through glass, paper, plastic, and similar materials; and they are absorbed by foods. Microwaves are produced inside the oven by an electron tube called a magnetron. The microwaves are reflected within the metal interior of the oven where they are absorbed by food. Microwaves cause water molecules in food to vibrate, producing heat that cooks the food.

That's why foods that are high in water content, like fresh vegetables, can be cooked more quickly than other foods.

Although heat is produced directly in the food, microwave ovens do not cook food from the "inside out. 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. Glass, paper, ceramic, or plastic containers are used in microwave cooking because microwaves pass through these materials. Although such containers cannot be heated by microwaves, they can become hot from the heat of the food cooking inside.

Some plastic containers should not be used in a microwave oven because they can be melted by the heat of the food inside. Generally, metal pans or aluminum foil should also not be used in a microwave oven, as the microwaves are reflected off these materials causing the food to cook unevenly and possibly damaging the oven.

The instructions that come with each microwave oven indicate the kinds of containers to use. They also cover how to test containers to see whether or not they can be used in microwave ovens. The FDA received reports in the past of serious skin burns or scalding injuries around people's hands and faces as a result of hot water erupting out of a cup after it had been overheated in a microwave oven.

Super-heated water water heated past its boiling temperature does not appear to be boiling and occurs when water is heated by itself in a clean cup. If super-heating has occurred, a slight disturbance or movement such as picking up the cup, or pouring in a spoon full of instant coffee, may result in a violent eruption with the boiling water exploding out of the cup.

Adding substances such as instant coffee or sugar before heating greatly reduces this risk. Users should closely follow the precautions and recommendations provided in the microwave oven instruction manuals, specifically regarding heating times. Users should make sure that they do not exceed the recommended heating times when determining the best time settings to heat water to the desired temperature.

Through its Center for Devices and Radiological Health CDRH , the FDA sets and enforces standards of performance for electronic products to assure that radiation emissions do not pose a hazard to public health. A Federal standard 21 CFR This limit is far below the level known to harm people.

Microwave energy also decreases dramatically as you move away from the source of radiation. The standard also requires all ovens to have two independent interlock systems that stop the production of microwaves the moment the latch is released or the door is opened. In addition, a monitoring system stops oven operation in case one or both of the interlock systems fail.

All ovens must have a label stating that they meet the safety standard. In addition, the FDA requires that all ovens have a label explaining precautions for use. This requirement may be dropped if the manufacturer has proven that the oven will not exceed the allowable leakage limit even if used under the conditions cautioned against on the label. To make sure the standard is met, FDA tests microwave ovens in its own laboratory. The FDA also evaluates manufacturers' radiation testing and quality control programs at their factories.

Microwave radiation can heat body tissue the same way it heats food.