Electromagnetic waves
A transverse wave caused by oscillations in an electromagnetic field. are transverse waves. Their vibrations or The repeated and regular fluctuations, above and below the same position, eg the pressure of a sound wave or the voltage of an alternating current. are changes in electrical and magnetic fields at right angles to the direction of wave travel.
All electromagnetic waves:
- transfer energy as Energy transferred as a wave聽spreading out from a source聽- eg light, infrared, sound. from the source of the waves to an absorber
- can travel through a A volume that contains no matter. such as in space
- travel at the same speed through a vacuum or the air
Electromagnetic waves travel at 300 million metres per second (m/s) through a vacuum.
Electromagnetic spectrum
Electromagnetic waves form a continuous A series of similar waves arranged in order of wavelength or frequency. of waves. This includes:
- waves with a very short The length of a single wave, measured from one wave peak to the next., high The number of waves produced each second. The unit of frequency is hertz (Hz). and high energy
- waves with a very long wavelength, low frequency and low energy
Electromagnetic waves can be separated into seven distinct groups in the spectrum.
Each group contains a range of frequencies. For example, visible light contains all the frequencies that can be detected by the human eye:
- red light has the lowest frequencies of visible light
- violet light has the highest frequencies of visible light