Key Concepts: Reflection & Refraction

Reflection

• Law of Reflection: Angle of incidence = angle of reflection (measured from the normal).
• Specular reflection: From smooth surfaces (mirrors) — clear image.
• Diffuse reflection: From rough surfaces — scattered in many directions.

Refraction

• Light bends when it passes from one medium to another due to a change in speed.
• Snell's Law: n₁ sin θ₁ = n₂ sin θ₂.
• Refractive index: n = c/v (ratio of speed of light in vacuum to speed in the medium).

Key Points

• Light bends toward the normal when entering a denser medium (n₂ > n₁).
• Light bends away from the normal when entering a less dense medium.
• Frequency is unchanged during refraction; wavelength changes.