Em waves and communication

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There are seven types of electromagnetic (EM) waves.

Electromagnetic radiation can occur at many different wavelengths.

In fact, there is a continuous spectrum of different wavelength, but waves with smaller wavelengths tend to have similar properties.

Electromagnetic radiation is conventionally spilt into seven types of waves.

All forms of electromagnetic radiation travel at the same speed through a vacuum. This means that waves with a shorter wavelength have a higher frequency.

About half the EM radiation we receive from the sun is visible light. Most of the rest is infrared (heat) with some UV thrown in. UV is what gives us a suntan.

The properties of EM waves depend on frequency and wavelength.

As the frequency and wavelength of EM radiation changes, its interaction with matter changes – i.e. the way a wave is absorbed, reflected and transmitted by any given substance changes.

As a rule, the EM waves at each end of the spectrum tend to be able to pass through material. Whilst those near the middle are absorbed.

Also, the higher frequency (shorter wavelength), like X-rays, tend to be more dangerous to living cells. That’s because they have more energy.

When any EM radiation is absorbed it can cause heating and ionisation (if the frequency is high enough). Ionisation is where an atom or molecule either loses or gains electrons and it can be dangerous.

Different sorts of signals have different advantages.

As well as cooking our food and keeping us warm, EM waves are used for communication. E.g. radio waves are used for radio, microwaves for mobile phones etc. before you communicate information through, it’s changed into electrical signal, which is then sent off on its own (like you get an ordinary phone line) or carried on an EM wave. The different types of signals have advantages and disadvantages:

1. Using light, radio and electrical signals is great because the signals are really fast.

2. Electrical wires and optical fibres can carry loads of information very quickly.

3. Information sent through optical fibres and electrical wire is pretty secure – they’re inside a cable and so can’t be easily tapped into. Radio signals travel through the air so can be intercepted more easily.

4. However, cable can be broken easily, so they need repairing.

5. Wireless communication also has the advantage that it is portable e.g. the device can be moved round.