Mrs Karina

rsMICROWAVES
Microwaves are radio waves with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz. Apparatus and techniquesmay be described qualitatively as "microwave" when the wavelengths of signals are roughly the same as the dimensions of the equipment, so that lumped-element circuit theory is inaccurate. The prefix"micro-" in "microwave" is not meant to suggest a wavelength in the micrometer range. It indicates that microwaves are "small" compared to waves used in typical radio broadcasting, in that they haveshorter wavelengths. Microwaves are good for transmitting information from one place to another because microwave energy can penetrate haze, light rain and snow, clouds, and smoke. Shorter microwavesare used in remote sensing. These microwaves are used for radar like the doppler radar used in weather forecasts. Microwaves, used for radar, are just a few inches long. We can use microwaves to cookfood or to communicate with others. Microwaves cause water and fat molecules to vibrate, which makes the substances hot.
Microwave frequency can be measured by either electronic or mechanicaltechniques. Frequency counters or high frequency heterodyne systems can be used. Accuracy of the measurement is limited by the accuracy and stability of the reference source. Mechanical methods require atunable resonator such as an absorption wavemeter , which has a known relation between a physical dimension and frequency.
EXPOSURE TO MICROWAVE RADIATION
Exposure to microwave radiation can producecataracts by this mechanism, because the microwave heating denatures proteins in the crystalline lens of the eye (in the same way that heat turns egg whites white and opaque). The lens and cornea of theeye are especially vulnerable because they contain no blood vessels that can carry away heat. Exposure to heavy doses of microwave radiation (as from an oven that has been tampered with to allow...