Positive And Negative Effects Of Electromagnetic Radiation - amazonia.fiocruz.br

Positive And Negative Effects Of Electromagnetic Radiation - think

At that time, many European physicists were experimenting with the cathode ray and numerous theories were being offered to explain its various characteristics phenomena. However, the most outstanding property of the cathode ray was discovered by Professor Roentgen. He found that when the cathode ray encountered matter, a new ray was produced which penetrated objects opaque to light and affect the photographic emulsions. While experimenting in his lab one day, Professor Roentgen turned on a Crooks-Hittorf cathode ray tube that was completely enclosed in black paper. Immediately a fluorescent screen that was some distance away began to glow. He found upon further experimentation that opaque objects held between the tube and the screen cast shadows upon the screen. Positive And Negative Effects Of Electromagnetic Radiation.

Positive And Negative Effects Of Electromagnetic Radiation - apologise, but

The most common health hazard of radiation is sunburn , which causes between approximately , and 1 million new skin cancers annually in the United States. Claims of harm from low levels of non-ionizing radiation sometimes described as "electrosmog" are unsupported by science. Dielectric heating from electromagnetic fields can create a biological hazard. For example, touching or standing around an antenna while a high-power transmitter is in operation can cause burns the mechanism is the same as that used in a microwave oven. The heating effect varies with the power and the frequency of the electromagnetic energy, as well as the inverse square of distance to the source. The eyes and testes are particularly susceptible to radio frequency heating due to the paucity of blood flow in these areas that could otherwise dissipate the heat buildup. Typical RF energy levels encountered by the general public are well below the level needed to cause significant heating, but certain workplace environments near high power RF sources may exceed safe exposure limits.

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Towards the same period at the end of 19th century, experimental investigations on conduction of electricity electric discharge through gases at low pressure in a discharge tube Electromaynetic to many historic discoveries. The discovery of X-rays by Roentgen inand of electron by J. Thomson inwas important milestones in the understanding of atomic structure.

It was found that at sufficiently low pressure of about 0. A fluorescent glow appeared on the glass opposite to cathode. The colour of glow of the glass depended on the type of glass, it being yellowish-green for soda glass. The cause of this fluorescence was attributed to the radiation which appeared to be https://amazonia.fiocruz.br/scdp/essay/benedick-and-beatrice-argument-quotes/business-ethics-of-microsoft-corporation.php from the cathode.

These cathode rays were discovered, inby William Crookes who later, insuggested that these rays consisted of streams of fast moving negatively charged particles. The British physicist J. Thomson confirmed this hypothesis.

By applying mutually perpendicular electric and magnetic fields across the discharge tube, J. They were found to travel with speeds ranging from about 0. This observation suggested the universality of the cathode ray particles.

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Around the same time, init was found that certain metals, when irradiated by ultraviolet light, emitted negatively charged particles having small speeds. Also, certain metals when heated to a high temperature were found to emit negatively charged particles. These observations thus established that all these particles, although produced under different conditions, were identical in nature.

Thomson, innamed these particles as electrons, and suggested that they were fundamental, universal constituents of matter. For his epoch-making discovery of electron, through his theoretical and experimental investigations on conduction of electricity by gasses, he was awarded the Nobel Prize in Physics in Inthe American physicist R. Millikan performed the pioneering oil-drop experiment for the precise measurement of the charge on an electron.

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He found that the charge on an oil-droplet was always an integral multiple of an elementary charge, 1. We know that metals have free electrons negatively charged particles that are responsible for their conductivity. However, the free electrons cannot normally escape out of the metal surface.]