… actually, not love but electromagnetic radiation is all around! Daniel Vlk Department of Biophysics Electromagnetic spectrum Dualism of matter – wave and particle nature of matter. (Evidences!) Electromagnetic radiation can be defined as transverse oscillations of an electromagnetic field which propagate in discrete quanta of energy which can be considered particles. These particles have zero rest mass, they are called photons. The basic properties of electromagnetic radiation are given by its energy which is directly proportional to the frequency of its oscillations and inversely proportional to their wavelength (Plank´s equation): E = hf = hc/λ Basic terms Electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields. The oscillations of the two fields are perpendicular to each other and perpendicular to the direction of energy and wave propagation. The wavefront of electromagnetic waves emitted from a point source (such as a light bulb) is a sphere. The position of an electromagnetic wave within the electromagnetic spectrum could be characterized by either its frequency of oscillation or its wavelength (next week lectures). Basic terms Electromagnetic radiation. B – magnetic flux density, E – intensity of electric field, λ = wavelength. = Speed of light: The speed (velocity) of light (in a vacuum) c is one of the most important physical constants: c = 299 792 458 m.s-1 ≈ 3×108 m.s-1 It is the highest speed which can be approached by a physical body with non-zero rest mass. The speed of light in vacuum was used for the modern definition of the meter: 1 meter is the distance which is travelled by light in vacuum during s. Dependence on medium! n … index of refraction v … speed of light in a certain medium Speed of Electromagnetic Radiation 299792458 1 v c n = Electromagnetic Spectrum – Interactions Photons – pair production Nukleus – NMR – MRI With the electron shell Electromagnetic Spectrum – Interactions Electron cloud (shell): Rayleigh scatter Excitation, Photoelectric effect and Compton effect (scatter) – later Electromagnetic Spectrum Electromagnetic Spectrum – Gamma rays and X-rays Ionizing radiation! Diagnostics Therapy Wavelenght 1nm – 400nm Electromagnetic Spectrum – UV Human: Vitamin D X Melanoma! Wavelenght 400nm – 800nm Vision! Electromagnetic Spectrum – Visible Light Circadian rhythm – biological clock! Wavelenght 800nm – 1mm Heat Movement from thermometry to thermography Electromagnetic Spectrum – IR Wavelenght 1mm – 1m Communication – Cell phones!!! Cooking - oven Medicine – physiotherapy… and indirectly Electromagnetic Spectrum – Microwaves Cyberknife Wavelenght 1m – 1km Communication – radio and TV Medicine – MRI! Electromagnetic Spectrum – Radio Waves Alternating currents! electricity network frequency: 50 – 60 Hz Electromagnetic Spectrum – AC !