in our lab, colorless light was one of the type of lights
Because the frequency of the light excites the electrons used in photosynthesis best.
Bear with me, this may be a little long. Colors of light aren't like colors in paint. In light, white light isn't the absence of color, it's the presence of ALL colors. And colored light isn't made by adding a color, instead you add a filter that takes away the colors you don't want. Plants can use light for photosynthesis, but what they use most are red and blue. That's why they look green, they absorb red and blue, but reflect green. The primary colors of light are red blue and green, so if you take away the red and blue, green is what's left.
