How is yellow colour formed?
Our brain can perceive a yellow color in one of two ways. Normal human eyes have three types of cone cells – one type responds to red light, another to green, and another to blue. Light of a single wavelength, about 580nm, will be perceived as yellow. The “red” and “green” cones actually have a very close spectral response, and yellow wavelengths of light will set off both types of cells, sending a signal to the brain that is interpreted as a yellow color. However, the exact same signal can be replicated by exciting the cone cells individually with both green and red light in the correct proportions. The brain gets the same information, and you see the same thing, yellow. Both beams of light would look yellow, but passing them through a prism would reveal a single yellow line for one and a red and green line for the other. Therefore, yellow is both a primary and secondary color. A yellow, transparent object absorbs blue light, allowing red through green wavelengths (red, orange, yellow
