⇒ Electromagnetic waves differ to the other types of waves seen (Waves - The Basics), because of instead of vibrating particles, here there are vibrating electric and magnetic fields
⇒ As seen above, there is a whole spectrum of electromagnetic waves, and they obey the same wave equation:
⇒ For electromagnetic waves, the speed will always equal 'c' (the speed of light). The speed of light is about 3 x 108 m/s
Different electromagnetic waves
⇒ Radio waves are used for long range communication and have a wave length of about 1 meter to 104 meters
⇒ Microwaves have a wavelength in the centimetre range (about 10-2 meters). These are used for communication with satellites as they pass quite easily through the atmosphere. Other ranges of microwaves are absorbed quite well by water so it can be used to heat up food that has lots of water in it, which is what your microwave does.
⇒ Infrared is about 10-5 meters and includes thermal radiation (e.g. heat lamps) and thermal imaging (e.g. in police helicopters to catch criminals)
⇒ Visible light is the electromagnetic wave you are most familiar with because you see it all the time as it is the one that eyes can detect
⇒ Ultraviolet is a type of ionising radiation and has a wavelength of about 10-8 meters. Ultraviolet is what gives you a sun tan
⇒ X-rays have a wavelength of 10-10 meters and are used for medical imaging as they pass straight through soft-muscle/skin but is absorbed by bones. It is also ionising, which is why you don't want to have too many x-rays.
⇒ Gamma rays have an extremely short wavelength of 10-15 meters and is even more ionising than x-rays so being exposed to lots of gamma rays can be very bad for you.
⇒ What happens when a wave hits a boundary between two materials? e.g. the boundary between glass and air (a window) or a boundary between air and water (surface of a pond)
⇒ It can do one of three things:
⇒ Mirror / smooth surface
⇒ Rough surface