Question

A ray of white light incident upon a glass prism is dispersed into various color components. Which one of the following colors experiences the least refraction?

• A. Red
• B. Yellow
• C. Orange
• D. Blue

Answer 1

The correct option is A

Red

Explanation of the correct option:

Option $A$:

1. The light waves are refracted as they enter and leave the prism.
2. The shorter the wavelength of the light, the more the refraction, since red light has the longest wavelength so it has the least refraction.
3. In simple language, we can say that the wavelength of the light and the refraction are inversely proportional to each other.
   $\mu =\frac{c}{v}$
4. The angle of deviation is given by $\delta =(\mu -1)A$ where $\delta$ is the angle of deviation, $\mu$ is the refractive index of the prism material, $A$ is the angle of prism.
5. The larger the refractive index, the larger the deviation angle.

Explanation of the incorrect options:

Option $B$:

No, it is incorrect because the wavelength of yellow color doesn't have the largest value and hence its bending will be greater than red.

Option $C$:

No, it is incorrect because the orange color has a wavelength less than red so when it passes the prism orange rays get more bent as compared to red.

Option $D$:

No, it is incorrect because the blue color has a very less wavelength, the amount of bending on blue rays is much more than the red rays.

Hence, the correct option is ($A$).