Upcoming SlideShare
×

# Nature of em wave

683 views

Published on

plus two physics

Published in: Technology
2 Likes
Statistics
Notes
• Full Name
Comment goes here.

Are you sure you want to Yes No
• Be the first to comment

Views
Total views
683
On SlideShare
0
From Embeds
0
Number of Embeds
3
Actions
Shares
0
37
0
Likes
2
Embeds 0
No embeds

No notes for slide

### Nature of em wave

1. 1. Nature of Electromagnetic Waves
2. 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. 3. It propagates (moves) through space carrying energy from one place to another
4. 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. 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. 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. 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. 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. 9. Electromagnetic waves or, For the electric field E, i.e. wave equation with v 2 = 1/µ o 
10. 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
11. 11. Solution of the equation
12. 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>