Question

The colour of light for which the refractive index of glass is minimum is:

• A. Red
• B. Yellow
• C. Green
• D. Violet

Answer 1

The Correct Option is A

Step 1: Understand refractive index and dispersion
Refractive index of a material depends on the wavelength (or colour) of the light passing through it.
When white light passes through a prism or glass, it splits into its constituent colours – this phenomenon is called dispersion.

Step 2: Relation between refractive index and wavelength
- The refractive index is inversely related to the wavelength of light.
- Shorter wavelength (like violet) → higher refractive index.
- Longer wavelength (like red) → lower refractive index.

Step 3: Conclusion
Among all the colours, red light has the longest wavelength, and hence, it has the minimum refractive index in glass.

Final Answer:
Red