Microwaves :: essays research papers

You might remember the heroic role thatnewly-invented radar played in the Second knowledge domainWar. People hailed it then as "Our Miracle Ally".But even in its earliest years, as it was helping winthe war, radar proved to be much than an expertenemy locator. Radar technicians, doodling awayin their idle moments, found that they could focus aradar dig on a marshmallow and toast it. They in addition popped popcorn with it. Such was thebeginning of microwave cooking. The very sameenergy that warned the British of the Ger valet de chambreLuftwaffe invasion and that policemen employ topinch speeding motorists, is what many of us nowhave in our kitchens. Its the same as what carrieslong distance ph matchless calls and cablevision. Hitlersarmy had its own version of radar, using radiowaves. But the anesthetise with radio waves is thattheir long wavelength requires a large,cumbersome antenna to focus them into a narrowradar beam. The British showed that microwaves,with their s hort wavelength, could be focussed inanarrow beam with an antenna many times smaller.This enabled them to make more effective use ofradar since an antenna could be carried onaircraft, ships and mobile ground stations. Thischaracteristic of microwaves, the might withwhich they are concentrated in a narrow beam, isone reason why they can be used in cooking. Youcan produce a high-powered microwave beam ina small oven, but you cant do the same with radiowaves, which are simply too long. Microwavesand their Use The idea of cooking with radiationmay seem like a fairly new one, but in fact itreaches back thousands of years. Ever sincemastering fire, man has cooked with infraredradiation, a close kin of the microwave. Infraredrays are what give you that warm glow when youput your hand near a room radiator or a hotplateor a campfire. Infrared rays, flowing from the sunand striking the atmosphere, make the Earth warmand habitable. In a conventional gasconade or electricoven, infrared wave s pour off the hot elements orburners and are converted to heat when theystrike air inside and the food. Microwaves andinfrared rays are related in that both are forms ofelectromagnetic energy. Both consist of electricand magnetic fields that rise and fall like waves onan ocean. Silently, invisibly and at the speed oflight, they travel through space and matter. Thereare many forms of electromagnetic energy (seediagram). Ordinary light from the sun is one, andthe only one you can actually see. X-rays areanother. Each kind, moving at a separatewavelength, has a unique effect on any matter it