Question

An object looks red when seen through a piece of red glass. What is the actual colour of the object ?
A. Red
B. White
C. Red or green
D. Black

Answer 1

Hint: We have to figure out the refractive index in both the mediums to get this answer. As we know that if there is no change in refractive index there should not be any change in the color of an object seen through a glass piece.

Complete step by step answer:
So now in this case, according to the question, when we see an object through a piece of red glass then the color of the object must be of the color it actually is because there is no change in refractive index of the medium and it is a constant value, So whatever maybe the color of the object only that color will be visible.
So, the color of the object must be red.
Therefore option A is the correct answer.

Additional Information:
We know that when we pass a monochromatic ray of light through a prism it splits into seven different colors and emerges from the prism, this is because a monochromatic white ray of light is made up of violet, indigo, blue, green, yellow, orange and red color, and these lights emerges out from the prism according to their wavelength as there is a change in wavelength the colors split out.
There are some laws that the phenomenon of refraction follows those are,
The incident ray, normal, and the refracted ray all lie on the same plane.
According to Snell’s laws of refraction, the ratio of the sine of the angle of incidence to the ratio of the angle of refraction is a constant value that is fixed for any two given mediums.
$\dfrac{\sin i}{\sin r}=\text{constant}$ .

Note:
Students must have a clear concept of refractive index, what is it and how is it calculated, what are the rules that the phenomenon of refraction follows. Students must also know the wavelength of some specific light rays as it will help them to solve the question.