EM waves

• 2 uses of gamma rays - treatment of cancer, sterilising medical equipment
• hazard of gamma rays - can cause cancer
• detection of gamma rays - Geiger Muller tube
• wavelength of gamma rays - 10 -12 m
• 2 uses of X-rays - medical images, security purposes
• hazard of X-rays - can cause cancer
• detection of X-rays - photographic film
• wavelength of X-rays - 10 -10 m
• mnemonic for EM wave spectrum - Raging Martians Invaded Venus Using X-ray Guns
• speed for EM waves - 3 x 10 8 m/s
• highest frequency EM wave - gamma rays
• lowest frequency EM waves - radio waves
• dispersion - splitting of white light into colours of the spectrum
• refraction - change of direction of a light ray when it passes accross a boundary between 2 transparent subsatnces
• transmission - a wave passing through a substance
• highest wavelength of visible light - red
• lowest wavelength of visible light - violet
• infrared wavelength - 1 x 10 -6
• a perfect black body is an object that absorbs all of the radiation on it
• the best emitter of infrared radiation is dull black
• the worst emitter of infrared radiation is shiny silver
• bigger blueshift - means the object is moving faster towards us
• radiowaves are used for communication
• microwaves can penetrate the atmosphere
• microwaves and radiowaves can be used in satellites
• bigger redshift means object is moving faster away from us