Prism dispersion increases deviation with frequency

Steps:

• Deviation angle δ = (n - 1)A, where n is refractive index and A is prism angle.
• Refractive index n increases with light frequency due to material dispersion.
• Higher-frequency blue light has greater n than lower-frequency red light.
• Therefore, δ increases as frequency increases from red to blue.

Why D is correct:

• D depicts δ rising with frequency, consistent with the dispersion relation where n ∝ frequency.

Why the others are wrong:

• A: Shows δ decreasing with frequency, contradicting higher n for blue light.
• B: Shows constant δ, ignoring frequency-dependent n.
• C: Shows δ peaking then falling, unsupported by prism optics.

Final answer: D