Classical View of LightEdit
The classical view of light is simply a wave. This wave has two orthogonal (perpendicular) components. These are an electric field and a magnetic field. In the diagram shown the light is traveling to the right, the electric field is in the same plane as the page, and the magnetic field is traveling in and out of the page. All three of these are perpendicular to each other. The electric and magnetic component share anti-nodes. Anti-nodes are the points where the wave passes through the zero and changes sign. Since both waves are similar it is possible to refer to the wavelength of light, and not just the wavelength of the electric component of light.
The Photoelectric effect is the emission of electrons from metal when it is shined on by light. The amount of electrons released depends on the type of metal and the frequency of the light. For some metals, if the light is below a certain frequency, it will not emit any electrons. Light was originally thought as a form of energy, but for this to be true, electrons would have been emitted, regardless of the frequency.