Waves - 6.2.1 Types of Electromagnetic Waves (GCSE Physics AQA)

Types of Electromagnetic Waves

Defining Electromagnetic Waves

We can define electromagnetic waves in the following way.

Electromagnetic waves form a continuous spectrum and all types of electromagnetic wave travel at the same velocity through a vacuum (space) or air.

EM Energy Transfers

• The electromagnetic spectrum is formed of waves, specifically transverse waves. Since the it is formed of waves, the spectrum will have the properties of waves.
• One of these properties is the ability to transfer energy from a source to an absorber. This fits with our definition that we mentioned previously; waves transfer energy and not matter.

An EM Energy Transfer Example

The commonest example of an EM wave transfer is the example of visible light.

Electromagnetic radiation comes from the Sun, transferring into the form of visible light. This visible light is made up of various frequencies. Each frequency will correspond to a colour of the rainbow, which is also called the spectrum of visible light.

When all these frequencies are combined, they will appear as white light. This is what we simply call ‘visible light’.

The Electromagnetic Spectrum

• We can split the EM spectrum up. Since the EM spectrum is formed of many different waves, we need to organise and split up these up. We can group these waves using various criteria.
• EM waves are grouped by wavelength and frequency. Commonly, we use the frequency and wavelength of each EM wave to split them into groups. EM waves with a long wavelength will have a low frequency, whilst those with a short wavelength will have a high frequency.
• There are 7 different EM waves. In total, there are seven different types of EM waves. This is a mnemonic to remember them: Rare Metals Include Vanadium Unlike Xenon Gas. As you can see, the EM waves have been arranged on the spectrum below from order of longest wavelength to shortest wavelength.

Human sight and EM Waves

• Human eyes are not very sensitive, which means that we can only see a small range of the whole electromagnetic spectrum. In fact, the only part of the spectrum that we can see is visible light. Visible light appears as various wavelengths on the spectrum. Each of these wavelengths will correspond to a different colour, but they will all combine to produce white light.