Which part of the light wave do we take? (quick question)

[scilearner]

Hello,

 

Quick question. This is a light wave

 

 

This is another light wave

 

 

Why doesn't this graph have another perpendicular graph. Are they talking about the particles in the magnetic field or electric field here or both.

 

Simply how do they make one wave out of a light wave that has two waves

[swansont]

The second graph is probably looking at the electric field; the amplitude of the magnetic field is proportional to the electric field, so there's really no new information contained by representing it.