The magnitude of the magnetic field produced depends on both the vibration rate of the electrical field and the speed at which the filed emanates from the vibrating charge Higher the speed, greater the magnetic field Energy is equally divided between electrical and magnetic that are perpendicular All EMR have the same velocity –3x10^8 m/sec History: radiated energy could NOT be emited with a continuous spectrum of energies, but was emitted with a specific quantum of energy Each emitted bundle of energy had a v specific quantum of energy associated with it Main points of photoelectric effect - bodies emit radiation (energy) as an EM wave - emission occurs as a pulse rather than as continuous event, and the pulse came to be known as a photon - photosn travel at the speed of light, also have freq an wavelength - energy of photon is proportional to its freq - radiant energy is propagated along a wave, but in a quanta of energy that behave like particles - photons have no mass at rest, but significant mass when moving at the speed of light Higher the frequency, higher the amount of energy. Hence the h constant (plank) Photons are quantized, tiny and massless products EM radiation is dualistic EM have wave-like properties EM radiation can be thought as a radiant energy transported in photons which are carried along by a wave field Eventually, everyone figured out that these types of radiation (cosmic rays, x rays, radio waves etc) are all the same but differ in frequency and energy involved Can be seen as a spectrum
Ionizing radiation is discussed in terms of energy While non-ionizing is described by wavelength Electromagnetic spectrum ranges from very high energy (tiny wavelength) to low energy (very long wavelength) When an emission interacts with a target, it transfers some or all of its energy to the target Ions cause chemical reactions in tissue, and all kinds of damage Bottom line – ionizing radiation causes ions to be formed in tissue and that causes health effects. More than 7.4 eV Ionization: on the EMR scale all radiation that is above about 10 eV is ionizing, so this included all cosmic rays, all y-rays, all x-rays and most UV rays On the EMR scale, all radiation that is above 10 eV is ionizing Neutrons, B-particles, a-particles, positrons are all energetic enough to cause ionization as well When the neutral atom loses an e-, It becomes an ion – actually, an ion pair Ions are v reactive As the particle continues to transfer energy to the targe, it will continue to creat ion pairs Each ion pair creation takes about 10 eV of energy Neutral atom: 2 p and 2 e- Ion: 2 p and 1 e- Common result from these interactions is the production of ion pairs in the material that absorbs the energy Humans have about 10^12 cells – what is the most common molecule in a cell Cels are mostly water – so the most common effect of absorbing radiation begins with the ionization of water
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