Choosing the Right Color: 1  Light color is measured on a temperature scale referred to as Kelvin (K). 2  Lower Kelvin numbers mean the light appears more yellow; higher Kelvin numbers mean the light is whiter or bluer. 3  Most ENERGY STAR certified bulbs are made to match the color of incandescent bulbs at 2200-3000K. For a whiter light, look for bulbs marked 3500-4100K. For bluer white light, look for bulbs marked 5000-6500K.
Visible Light. Visible Light Waves Visible light waves are the only electromagnetic waves we can see. We see these waves as the colors of the rainbow. Each color has a different wavelength. Red has the longest wavelength and violet has the shortest wavelength. When all the waves are seen together, they make white light.
The red light along one edge of the rainbow is electromagnetic radiation with a wavelength of about 620 to 750 nanometres; the violet light along the opposite edge is radiation with a wavelength of 380 to 450nm. But there is far more to electromagnetic radiation than these visible colours.