Wavelength-Dependent Refraction in Prisms

Steps:

• Light refracts when entering the prism due to speed change from air to glass.
• Speed in glass is v = c/n, where n (refractive index) decreases with increasing wavelength.
• Red light (longer wavelength) has lower n than blue, so higher v in glass.
• Lower n for red causes smaller deviation angle, leading to less refraction and dispersion.

Why A is correct:

• Snell's law (n1 sin θ1 = n2 sin θ2) shows lower n for red results in smaller θ2, meaning less bending; red's higher v means less slowing than blue.

Why the others are wrong:

• B: Red is not slowed more; it slows less due to lower n.
• C: Red is neither slowed nor refracted more; both are less than blue.
• D: Red is slowed less but not refracted more; refraction is less.

Final answer: A