* TV and FM radio (short wavelength)
* Direct line of sight with transmitter (do not diffract) * Medium wavelength – travel further because they reflect from layers in the atmosphere * Used for transmitting signals.
* Microwaves are used in satellite television broad casting. * It is used to transmit mobile phone signals between Mast, which may be up to 20km apart. * Microwaves are absorbed by water molecules.
* These water molecules become heated so they heat food
* Used for Cooking
* It is used for night vision and security cameras as Infrared Radiation is visible in daytime or night-time * Police use it to catch criminals, army use it to detect enemy * Used to see body heat.
* It is used in remote controls for devices such as televisions and video recorders.
* UV synthesizes vitamin D in skin, controls the endocrine system and is a painkiller. * Used in state of the art air-handling units, personal air purifiers and swimming pool technology. * Used to detect forged bank notes: they fluoresce in UV light; real bank notes don’t. Used to identify items outside visible spectrum areas, known as 'black lighting'. * Used in policing and reading secret messages etc
* X-rays detect bone breaks
* X-rays pass through flesh but not dense material like bones * X-rays can penetrate solid materials and so they are used in security scanners at airports. * They are used in hospitals to see inside patients without having to perform surgery.
* Gamma Rays cause and treat cancers
* In high doses, gamma can kill normal cells and cause cancers * Gamma can be used to kill mutated cells though too.
Properties common to all electromagnetic waves
* They are all transverse waves.
* Travel at the same speed...