| MadSci Network: Physics |
Hello: My answer will be based upon an engineering perspective of particle physics. Light, or photon, is a particle with dual physical properties: it behaves as a particle, also as a wave. Man can view a narrow frequency range of the (wave) spectrum, low frequency red to high frequency violet. The sun generates higher frequency particles are filtered by the earth's protective shield of ionized oxygen in the troposphere (ozone layer) and prevents harm to organisms such as ours. This filtering allows some harmful radiation to pass through, namely ultra-violet and beyond. In the broad sense they are referred to as "rays" such as alpha, beta, and gamma rays. Gamma rays are the most harmful because of high energy levels they act as painless micro-bullets. Lower frequency ultra-violet rays affect skin pigmentation producing sun-tan or burning the outer layer of skin if it is devoid of protective pigment. In the mid 40's physicists experimented with accelerating electrons by means of pulsating magnetic fields and found that certain resonances occur producing high energy beta rays in so-called betatrons. They achieved energy levels of 2,000,000 electron-volts (a quatitative way to express particle energy). Modern, mobile, betatrons producing in excess of 6 million electron-volts are used in Non-Destructive Testing (NDT) to examine flaws within impenetrable objects such as metal and pavement without ill effects. The same technique is used with ultrasound to dynamically examine (image) the human body internal organs. I had poor luck finding simple explanations in the web, but you might look at . Good luck, MAD MICRO.
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