2 ELECTROMAGNETIC RADIATION -Electromagnetic radiation is one of the many types of energy and may appear in the form of visible light, x-ray, infrared radiation or radio wave.-The SI unit of radiation is electron volte(eV)- Electromagnetic radiation vary in energy, frequency, and wave length:
3 Electromagnetic radiation vary in energy, frequency, and wave length
4 Electromagnetic radiation vary in energy, frequency, and wave length
5 Characteristics of electromagnetic radiation -Electromagnetic radiation consists of vibrations in electric and magnetic fields, These vibrations:-- Have no charge- No mass- Travel at the speed of light.- Moves in sinusoidal waves.- Electromagnetic radiation is described in terms of Velocity (c), Frequency (ƒ), Period (T), Wavelength (λ) and Amplitude
6 Velocity (c)-All electromagnetic radiation in vacuum travels at 3*108 meter per second.
7 Frequency (ƒ)-The frequency (ƒ) of a wave is the number of cycles per second (T). ƒ = 1/T The unit of frequency is the hertz (Hz) which equal one cycle per second.
8 Period (T):-It is the time required for one complete cycle. - A wave with a frequency of 2 cycles per second has a period of 1/2 second
9 Wavelength (λ) It is the distance between adjacent peaks of a waves. Electromagnetic radiation with shorter wavelengths will have higher energy and frequencies and greater penetration.- Wavelength is measured in meters, centimeters or millimeters.
10 Wavelength (λ)Electromagnetic wave velocity, frequency, and wavelength are related by:-C = ƒ λC = the speed of light.ƒ = the frequency.λ = lambda is the wavelength.Frequency and wavelength are inversely proportional
12 Amplitude-The amplitude of a wave is the maximum height, or difference from zero (in either direction) of the peaks.
13 Quantum theoryElectromagnetic radiation can act as a wave or a particle. When electromagnetic radiation acts as a particle, that particle is called a photon.-The energy E of a photon is related to it is frequency by:E= h ƒ E=h c/λh =constant.C = the speed of light.ƒ = the frequency.λ = lambda is the wavelength.
14 Radiation intensity and the inverse square law All electromagnetic radiation travels at the speed of light and diverges from the source at which it is emitted.Intensity is energy flow per centimeter square and is measured in watts per centimeter square (W/cm2).-The intensity of the radiation decreases with an increase in the distance from the source.
15 Radiation intensity and the inverse square law -This relation known as the inverse square law, because the intensity is inversely proportional to the square of the distance. I2 / I1 = (d1/d2)2 I2 = intensity at distance d2 I1 = intensity at distance d1
16 Radiation intensity and the inverse square law Thus, the intensity is inversely related to the distance. If distance from x-ray source is doubled the intensity decreases by a factor of 4.
17 inverse square lawThe Celsius & Fahrenheit scales are based on the phase transition temperatures for pure water