Dispersion of white light by refraction in a prism

Steps:

• White light consists of multiple wavelengths, each with different speeds in the prism material.
• Shorter wavelengths (violet) refract more than longer ones (red) due to higher refractive index.
• This causes angular separation, forming a spectrum with violet deviated most and red least.
• The diagram must show rays emerging in correct color order from the prism face.

Why C is correct:

• It depicts the spectrum with violet ray bent most and red least, matching Snell's law where deviation angle increases with refractive index for shorter wavelengths.

Why the others are wrong:

• A shows no dispersion, with all rays parallel post-prism, violating wavelength-dependent refraction.
• B reverses color order, placing red deviated most, contrary to violet's higher deviation.
• D shows convergence of rays, indicating focusing rather than spreading into a spectrum.

Final answer: C