2.
<ul><li>Electromagnetic radiation is a disturbance in an electric field. </li></ul><ul><li>This results in a magnetic field at right angles to the electric one. </li></ul><ul><li>Therefore it is called an electromagnetic radiation – electric and magnetic disturbances result! </li></ul>
3.
It propagates (moves) through space carrying energy from one place to another
4.
<ul><li>All electromagnetic waves (also called electromagnetic photons) can travel through a vacuum – it is the only way that energy can propagate through space </li></ul>
5.
<ul><li>Wavelength is the smallest distance between two corresponding points on a wave. </li></ul><ul><li>It is given the symbol and is measured in metres. </li></ul>
6.
The wave equation <ul><li>wave speed (metre/second, m/s) = frequency (hertz, Hz) × wavelength (metre, m) </li></ul><ul><li>wavespeed = f </li></ul>
7.
<ul><li>All electromagnetic radiation travels through a vacuum at the same speed – the speed of light – symbol ‘c’ – which is 300,000,000 m/s </li></ul><ul><li>This is the fastest speed anything can travel at! </li></ul>
8.
<ul><li>As electromagnetic waves all travel at the same speed and: </li></ul><ul><li>c = f </li></ul><ul><li>If a wave has a long wavelength it must have a low frequency and vice versa a high frequency wave must have a short wavelength… f and have to always equal 300,000,000 when they are multiplied together. </li></ul>
9.
Electromagnetic waves or, For the electric field E, i.e. wave equation with v 2 = 1/µ o
10.
Electromagnetic waves Similarly for the magnetic field i.e. wave equation with v 2 = 1/µ o c = 3.0 X 10 8 m/s
12.
Irradiance (energy per unit volume) <ul><li>Energy density stored in an electric field </li></ul><ul><li>Energy density stored in a magnetic field </li></ul>
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