Question

When a green leaf is seen in red light, it will appear
1. Black in colour
2. Blue in colour
3. Green in colour
4. Red in colour

Answer 1

Correct Answer - Option 1 : Black in colour

The correct answer is black in color.

• A green leaf can only reflect green light, so when the red light is incident on it, the leaf will not be able to reflect any light making it look black

• It would appear black, just as any other green object would.
• The color green appears green because it reflects green wavelengths.
• Red wavelengths are much longer than green, and when only red light hits a green object, the red is absorbed and very little of the light is reflected back, so therefore the color appears black.
• When light hits a leaf the chlorophyll absorbs and uses the red and blue wavelengths and reflects back the green light to your eye, since it doesn’t use much of it.
• Absorbs all wavelengths of the visible light spectrum except the green color, and therefore it appears green as they reflect it.
• But when solely red light is given to the leaf, it will absorb the red light and therefore appears as black.
• As we know when all the wavelengths of the spectrum are absorbed, the subjected object appears black; and if they appear white, that means the object reflects the incident light.