Light is just a small part of the spectrum of electromagnetic waves. Our eyes can only detect light and not the rest of the spectrum.
In a vacuum, all electromagnetic waves travel at the speed of light, c, which = 3.0*10^8ms^-1. Wavelength of electromagnetic radiation of frequency f in a vacuum is given by;
λ = c/f
Note; light wavelengths are often expressed in nanometres (nm), where 1nm = 0.000000001m = 10^-9m.
Main parts of the electromagnetic spectrum;
Type Wavelength Range
Microwave 0.1m to 1mm
Infrared 1mm to 700nm
Visible 700nm to 400nm
Ultraviolet 400nm to 1nm
Gamma rays <1nm
An electromagnetic wave consists of an electric wave and a magnetic wave which travel together and vibrate;
- at right angles to each other and to the direction in which they are travelling.
- in phase with each other. The two waves reach a peak together so are in step, meaning…