1. Electromagnetic Waves
Physics 014
Electromagnetic Waves

2. Maxwell’s Rainbow
Using Maxwell’s Equation’s we find that light is just made of alternating electric and magnetic fields
There is a huge spectrum of electromagnetic waves

3. Maxwell’s Equations

4. Maxwell’s Rainbow

5. Traveling EM Waves Electromagnetic waves are a type of radiation
We will consider waves with wavelengths approximately 1 m

6. Traveling EM Waves
How is the wave created?

7. Traveling EM Waves The LC oscillator has an angular frequency ω
This will correspond to the frequency of the EM wave
The dipole antenna produces a varying E field

8. Traveling EM Waves

9. Traveling EM Waves We can write the fields as Wave number Amplitude
Angular frequency

10. Traveling EM Waves
All electromagnetic waves, including visible light, have the same speed c in vacuum

11. Poynting Vector
Energy transport per unit area in a wave is described by the Poynting vector S

12. Poynting Vector
What is most useful is the intensity I of the wave

13. Reflection and Refraction
Although light spreads as it travels from a source, it can often be represented as traveling in a straight line
This is called the geometrical optics approximation

14. Reflection and Refraction

15. Reflection and Refraction
Law of reflection
Law of refraction

16. Reflection and Refraction
The constants n1 and n2 are called the index of refraction
It is the ratio of c (speed of light in vaccum) to the speed of light in the material

17. Reflection and Refraction
In certain cases all the light is reflected.
This is called total internal reflection

18. Reflection and Refraction