We are able to see objects because of the light reflected from them is perceived by our eyes. Objects absorb certain wavelengths and reflect the other. It is the color of the reflected wavelengths which imparts color to the objects. Now, grass absorbs the other colors of light and reflects green light. This green light reaches our eyes when we look at grass. Thus grass is green.wi
Since the green filter will block out green light, no color will reach our eyes and the grass will look black.