Electromagnetic Waves Physics 014 Electromagnetic Waves

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

Maxwell’s Equations

Maxwell’s Rainbow

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

Traveling EM Waves How is the wave created?

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

Traveling EM Waves

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

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

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

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

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

Reflection and Refraction

Reflection and Refraction Law of reflection Law of refraction

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

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

Reflection and Refraction