The Sun

We concentrate visible light to make lasers to use in everything from surgery, to CD players to laser pointers. Visible light waves also make our TV, computer and cell phone screens work.

Light with a wavelength immediately shorter than any light in the visible spectrum is called Ultraviolet Light.

The different wavelengths of visible light are seen as the colors of the rainbow: red, orange, yellow, green, blue, indigo, and violet. The longest wavelengths (around 700 nanometers) are red and the shortest wavelengths (380 nanometers) are violet.

Sound is the most important example of a mechanical wave. Sound waves cannot travel through a vacuum.

One way to categorize waves is on the basis of the direction of movement of the individual particles of the medium relative to the direction that the waves travel. Categorizing waves on this basis leads to three notable categories: transverse waves, longitudinal waves, and surface waves.

Mechanical Waves are waves which propagate through a material medium (solid, liquid, or gas) at a wave speed which depends on the elastic and inertial properties of that medium. There are two basic types of wave motion for mechanical waves: longitudinal waves and transverse waves.

The frequency, represented by the Greek letter nu (ν), is the number of waves that pass a certain point in a specified amount of time. Typically, frequency is measured in units of cycles per second or waves per second. One wave per second is also called a Hertz (Hz) and in SI units is a reciprocal second (s−1).

The formula for frequency is: f (frequency) = 1 / T (period). f = c / λ = wave speed c (m/s) / wavelength λ (m).