The colors of transparent objects is determined by colors of light transmitted by them.
A transparent red filter held against White light appears red as it absorbs all colors except Red which is transmitted to the eye.
If a Red filter is held against Green light it will appear black as it absorbs the Green light.
If a Red flower is viewed through a Green filter, it will appear black since the Red light from flower is not transmitted by Green filter.
Thumb Rule: If there is a common color in the incident light and the filter, then the filter will appear to be of common color. Otherwise it will appear black.
A transparent red filter held against White light appears red as it absorbs all colors except Red which is transmitted to the eye.
If a Red filter is held against Green light it will appear black as it absorbs the Green light.
If a Red flower is viewed through a Green filter, it will appear black since the Red light from flower is not transmitted by Green filter.
Thumb Rule: If there is a common color in the incident light and the filter, then the filter will appear to be of common color. Otherwise it will appear black.
