NM (Nanometer) unit of length in the metric system. Equal to one billionth of a metre.
THz (Terahertz): is a unit of electromagnetic (EM) wave frequency equal to one trillion hertz. THz is used as a measurement of the frequency of infrared (IR), visible, and ultraviolet (UV) radiation.
One trillion hertz (10^12)
- In the 17th century Scientist Newton discovered visible lights after testing light in a prism.
- The color of an object that we see is the color of light reflected. All other colors are absorbed.
The Sun is a natural source for visible light waves and our eyes see the reflection of this sunlight off the objects around us.