what are the causes of radiation?
600593
radiation according to me is due to excitation of electrons from lower energy levels to higher levels and vice versa.During exitation electrons obsorb or release energy in form of packets called quanta which will travel in form of waves
1165741
Blast and thermal effects occur to some extent in all types of explosions, whether conventional or nuclear. The release of ionizing radiation, however, is a phenomenon unique to nuclear explosions and is an additional casualty producing mechanism superimposed on blast and thermal effects. This radiation is basically of two kinds, electromagnetic and particulate, and is emitted not only at the time of detonation (initial radiation) but also for long periods of time afterward (residual radiation). Initial or prompt nuclear radiation is that ionizing radiation emitted within the first minute after detonation and results almost entirely from the nuclear processes occurring at detonation. Residual radiation is defined as that radiation which is emitted later than 1 minute after detonation and arises principally from the decay of radioisotopes produced during the explosion. \n\nAbout 5% of the energy released in a nuclear air burst is transmitted in the form of initial neutron and gamma radiation. The neutrons result almost exclusively from the energy producing fission and fusion reactions, while the initial gamma radiation includes that arising from these reactions as well as that resulting from the decay of short-lived fission products. The intensity of initial nuclear radiation decreases rapidly with distance from the point of burst due to the spread of radiation over a larger area as it travels away from the explosion, and to absorption, scattering, and capture by the atmosphere. The character of the radiation received at a given location also varies with distance from the explosion. Near the point of the explosion, the neutron intensity is greater than the gamma intensity, but with increasing distance the neutron-gamma ratio decreases. Ultimately, the neutron component of initial radiation becomes negligible in comparison with the gamma component. The range for significant levels of initial radiation does not increase markedly with weapon yield and, as a result, the initial radiation becomes less of a hazard with increasing yield. With larger weapons, above 50 Kt, blast and thermal effects are so much greater in importance that prompt radiation effects can be ignored. \n\nBlast and thermal injuries in many cases will far outnumber radiation injuries. However, radiation effects are considerably more complex and varied than are blast or thermal effects. A wide range of biological changes may follow the irradiation of an animal, ranging from rapid death following high doses of penetrating whole-body radiation to an essentially normal life for a variable period of time until the development of delayed radiation effects, in a portion of the exposed population, following low dose exposures. When comparing the effects of radiation, that dose which is lethal to 50% of a given population is a very useful parameter. The term is usually defined for a specific time, being limited, generally, to studies of acute lethality. The common time periods used are 30 days or less for most small laboratory animals and to 60 days for large animals and humans. On occasion, when a specific type of death is being studied, the time period used will be shorter. The specified period of time is indicated by a second number in the subscript; LD50/30 and LD50/5 indicate 50% mortalitywithin 30 days and 5 days, respectively. The LD50 is a median,
699805
It is caused by electrons being emitted...(aka photons aka light) but certain metals give off certain colours according to their wavelenght...and according to the line spectrum....
758598
Gamma rays, heat and, in the case of a few highly-radioactive elements, light; they glow in the dark.  Beta particles which are high-energy electrons.   Their kinetic energy can be converted into light by a phosphor such as zinc sulphide, or if they enter a transparent medium with a high refractive index, they emit blue Cerenkov radiation.  Radioactive materials are warmer than their surroundings because alpha particles, beta rays and neutrons are all fast-moving particles and when they are absorbed their kinetic energy is converted into heat.  In a nuclear reactor the heat is used to raise steam which drives a turbine.  In the thermionic generators used on deep space probes it is converted directly into about 200 watts or so of electricity.
340361
Refer to an electromagnetic spectrum.\nRadiation is emission and propagation and emission of energy in the form of rays or waves (http://dictionary.reference.com/search?q...\nIn other words as long as waves travel there is radiation.\nThere are two types of radiation, the ionizing (harmful) radiation and the non-ionizing (not harmful) radiation.\nYou can see it in a magnetic spectrum. High frequency and low wavelength are those ionizing radiation. High wavelenth and low frequency are those non-ionizing radiation. Penetration of these waves are dependent on their frequencies. High frequencies are able to tranmsmit objects.\nFrom the magnetic spectrum there are different kinds of waves, (from non-ionizing to ionizing) radiowaves, microwaves, infrared, white light, UV, x-rays, gamma rays cosmic rays. These waves travel in a straight line unless scattered by hitting an object or being blocked or interrupted or you know I mean.\nThat's why astronomers detect radiowaves from the outerspace.
393218
They emit radiation before being burnt, too.  They're made with a thorium alloy, and thorium is a weak alpha ray emitter similar to uranium.  I'm not sure if newer ones are made this way, but they were made with thorium for decades.
196945
Exposure to sunlight can (obviously) cause burns.  Over time, over-exposure can lead to cancer, as harmful solar radiation causes mutations in the DNA of your skin cells.  Sunight can also burn your retinas by being magnified by the lenses within your eyes.  Blindness can occur.\n\nOn the bright side, without sunlight we would all die by freezing to death.  If we could somehow survive that, we would then all die because without the sun, plants could not take carbon dioxide out of the air and create oxygen for us to breathe.  Sunlight is also needed in the production of vitamin D in our bodies.  Strangely, vitamin D helps against overproduction of cells, which is cancer!\n\nSunlight can both create AND prevent cancer!  You gotta love our sun!
1089990
(m)\n\nEnergy in the form of electromagnetic waves or particles capable of damaging cells by removing electrons from atoms or molecules. This damage can lead to cancer or other defects.
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Fossil fuel power plants can emit many harmful pollutants, ranging from Nitrogen Oxides and particulates to heavy metals & mercury.\n\nThe radiation from the sun's nuclear fusion is what gives us solar energy, but it can also cause skin cancer.\n\nUse of solar energy generally requires using materials that have caused pollution as a byprodouct of their manufacture.
686010
If you are talking about the effects of radioactive material (alpha, beta and gamma particles) on the human body then in layman's terms prolonged exposure would lead to burns, radioactive sickness - the bodies organs deteriorate and collapse, hair and teeth start to fall out and various cancers and other serious heavy metal / radioactivity induced conditions develop, etc.
88034
The risk of cancer increases if people are exposed to carcinogens (factors causing cancer,ex radiation)
356811
Cherenkov radiation is Electromagnetic (non-ionising) radiation emitted when a charged particle (e.g. an Electron ) passes through a medium (e.g. water) at a speed greater than that of light in the medium. This can be seen as the characteristic "blue glow" where sources of large activity (e.g. irradiator sources or spent nuclear fuel) are stored under water.\n\nI too have recollections that Cherenkov radiation is primarily asscoiated with Caesium, but I haven't managed to find any confirmation of this.
766097
They all put out radiaton which can cause cancer
632113
Nonionizing radiation is electromagnetic radiation that includes: \n\nRadio waves \nMicrowaves \nInfrared light \nVisible light \nHazards of Nonionizing Radiation\n\nUnlike ionizing radiation, nonionizing radiation does not have enough photon energy to remove an electron from an atom. However, it can still be hazardous. For example: \n\nPowerful industrial lasers, which emit tightly focused or coherent beams of visible light, can burn through human tissue and even metal. \nSome nonionizing radiation can interfere with the operation of heart pacemakers and other medical devices, as well as critical equipment in aircraft. \nHigh levels of radio frequency and microwave radiation can heat tissue and if the temperature increase is high enough, can adversely affect health. \nElectric and Magnetic Fields\nExtremely low-frequency electric and magnetic fields (EMFs) surround electrical machinery, home appliances, electric wiring, and high-voltage electrical transmission lines and transformers. (Figure 11) \n\nA good deal of public and government attention has been focused in recent years on the possible health effects of EMFs. The public is exposed to these fields through the generation, transmission, and use of electric power. The National Institute of Environmental Health Sciences (NIEHS), a branch of the National Institutes of Health (NIH), has compiled information on this issue. (You can get more information on this and other issues from the NIEHS Web site http://www.niehs.nih.gov/emfrapid) \n\nHigh-voltage power transmission and distribution lines have been a major focus of concern. Alternating-current (AC) electricity, with a frequency of 60 cycles per second, falls into the extremely low frequency range on the electromagnetic spectrum and thus has far too little energy to cause ionization. \n\nHowever, AC electric and magnetic fields can induce electric currents in conducting materials, including human and animal tissue. (Direct-current fields, such as the Earth's magnetic field, do not have this effect). The electric current induced in our bodies may have potential biological and health effects. \n\nEvidence of health effects from EMF is inconclusive, although some studies have indicated a possible link between EMFs and childhood leukemia and other forms of cancer. The information available, however, is not sufficient to establish a cause-effect relationship. \n\nSome studies have reported the possibility of increased cancer risks, especially leukemia and brain cancer, for electrical workers and others whose jobs require them to be around electrical equipment. Additional risk factors, however, such as exposure to cancer-initiating agents, may also be involved. \n\nSome researchers have looked at possible associations between EMF exposure and breast cancer, miscarriages, depression, suicides, Alzheimer's disease, and Amyotrophic Lateral Sclerosis (ALS, or Lou Gehrig's Disease), but the general scientific consensus is that the evidence is not yet conclusive. \n\nIn June of 1998, a special review panel convened by the NIEHS reviewed EMF health studies. A majority of the panel found "limited evidence that residential exposure to extremely low frequency magnetic fields may increase the risk of childhood leukemia." A majority also found limited evidence that workplace exposure to EMFs may cause chronic lymphocytic leukemia in adults. \n\nAccording to NIEHS, "the probability that EMF exposure is truly a health hazard is currently small. The weak epidemiological associations and lack of any laboratory support for these associations provide only marginal scientific support that exposure to this agent is causing any degree of harm." The NIEHS did conclude, however, in its 1999 Report to Congress, that extremely-low-frequency EMF exposure cannot be recognized as entirely safe because of weak scientific evidence that exposure may pose a leukemia hazard; the associations reported for childhood leukemia and ad
689133
gamma radiation i think. alpha and beta are relatively weak.
445826
some heavy materials emits the rays in spontaneously this is called radioactivity. this is accidentally found by Henry Becquerel
838075
We will assume you mean ionizing radiation rather than just light or radio waves. OK? \n\nPositive effects:\n1. Useful for imaging parts of the body and other objects normally not seeable. Examples: x-rays for bones, CAT scans for softer tissue, x-rays and gamma ray for machine parts, even neutrons for things like bomb and other carbon-based images.\n2. Useful for sterilizing material that cannot be subjected to high heat or chemicals. This includes delicate plastics and medical equipment. \n3. Useful for killing tumors and cancers. Rapidly dividing cells are more susceptable to the effects of radiation. Cancer cells can be killed without harming surrounding tissue as much.\n\nNegative effects\n1. Killing beneficial organisms. Radiation if delivered in an unmonitored, uncontrolled way can kill humans, other animals, and plants.\n2. Mutating cells. This can cause lethal effects or if not, it can cause cancer. One of the strangest paradoxes of radiation is that it is both a cause and a cure for cancer.\n3. Disrupting the physical properties of materials. Radiation can cause plastics and steel to become brittle and to eventually break.