Notes 22.2 - Vision and Color

White light is a combination of all of the colors of the rainbow. Red, orange, yellow, green, blue, indigo, and violet (ROY G BIV) Theses colors are known as “visible light”

Light energy comes in tiny bundles called photons. The color we see is dependent on the energy of the light. Red light is low energy. (Lower frequency/longer wavelength) Violet light has high energy (Higher frequency /shorter wavelength)

Just like our ears are only sensitive to a certain range of frequencies, so are our eyes. Visible light is a transverse wave with frequencies between 460 trillion Hz and 640 trillion Hz We can’t see if the frequencies are too low (infrared) or too high (ultraviolet).

Light that enters your eye lands on the retina. On the retina are millions of light sensitive cells called photoreceptors.

There are 2 types: Cones - 3 types each responding to either red, green or blue. If all 3 are stimulated, we see white Rods - respond to different intensities of light, not color. Only the rods work in low very dim light Rods outnumber cones 20 to 1

Additive primary colors : red, green and blue We perceive different colors as a combination of these 3 colors. R + G = yellow R+ B = magenta G + B = cyan R + G + B = white Ex: we see yellow when our red and green cones are stimulated, but not blue.

Different animals have different numbers and kinds of photoreceptor cells, so their vision is different. Dogs and cats don’t have 3 types of cones Some birds and insects can “see” UV light Primates have vision very similar to us.