Microwave radiation cooking with

Radiation with long wavelengths falls in the infrared, microwave, or radio frequency regions. Heat lamps make use of infrared radiation, microwave ovens cook with microwave radiation, and radio and television signals are transmitted by radio waves. 

Electromagnetic radiation can be absorbed or emitted. The absorption of ultraviolet radiation by our skin may cause sunburn. When we cook food in a microwave oven, the absorption of microwave radiation by the water in the food causes the water molecules to vibrate, generating heat that cooks the food. However, when electromagnetic radiation is absorbed or emitted by matter, it behaves more like a stream of particles than as a wave motion. These particles are called photons and so electromagnetic radiation can be considered both as a stream of photons and as waves with characteristic properties, such as wavelength (1) and frequency (/). Therefore we say that electromagnetic radiation has a dual nature wave motion and streams of photons. 

We are all familiar with use of microwave radiation in cooking food where it increases the speed of reaction. Recently this method has been used to synthesize solid state materials such as mixed oxides. The first solid state reaction experiments were performed in modified domestic ovens, and these are still used, but more specialised (and expensive ) ovens have also been developed to give more control over the conditions. We shall briefly consider how microwaves heat solids and liquids because this gives us insight into which reactions will be good candidates for this method. 

You come into contact with many different kinds of electromagnetic radiation in your daily life. For example, you use visible light to see the words on this page, you may cook with microwaves, and you should use sunscreen to protect your skin from the harmful effects of ultraviolet radiation. 

It is almost a certainty that you are familiar with microwave radiation—have you ever cooked or heated food in a microwave oven Microwave radiation plays a prominent role in a branch of science called rotational (or microwave) spectroscopy. For a discussion of rotational spectroscopy and how it is used not only to make precise measurements of bond lengths but also to detect molecules in interstellar space, go to the Focus On feature for Chapter 10, Molecules in Space Measuring Bond Lengths, on the MasteringChemistry site. 

Exposure to strong radiofrequency or microwave fields can cook tissue and produce deep internal bums. Exposure to X rays and to the radiation from radioactive materials must be carefully guarded against in experiments dealing with them. Any such experiments should be done under the direct supervision of an experienced research worker, who will assume personal responsibility for all required safety measures, and under an appropriate license if radioactive materials are involved. 

The cooking action in a microwave oven results from the interaction between the electric field component of the radiation with the polar molecules—mostly water—in food. All molecules rotate at room temperature. If the frequency of the radiation and that of the... 

The cooking action in a microwave oven results from the interaction between the electric field component of the radiation with the polar molecules— mostly water—in food. AH molecules rotate at room temperature. If the frequency of the radiation and that of the molecular rotation are equal, energy can be transferred from the microwave to the polar molecule. As a result, the molecule will rotate faster. This is what happens in a gas. In the condensed state (for example, in food), a molecule cannot execute the free rotation. Nevertheless, it still experiences a torque (a force that causes rotation) that tends to align its dipole moment with the oscillating field of the microwave. Consequently, there is friction between the molecules, which appears as heat in the food. 

Microwave and high radio frequency radiation are found in radar, communications, and cooking operations. Microwaves interact with the body by raising the temperature of body organs. It is suspected that the brain, the eyes, and the reproductive organs are vulnerable. 

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