Study Guides/Physics/Law of Reflection of Light
Study Guide · Physics

Law of Reflection of Light

When a ray of light hits a shiny, smooth surface (like a mirror), it bounces back into the same medium. This bouncing of light is called reflection. This physical phenomenon strictly obeys two fundamental rules, known as the Laws of Reflection.

Question (Click to Flip)

What is Diffuse Reflection?

Answer

When light hits a rough surface (like a wall), the rays reflect in many different random directions. This is diffuse reflection. However, at every microscopic point, the Laws of Reflection are still strictly obeyed.

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Key Facts

If you shine a laser directly straight down the normal line (at a 0-degree angle of incidence), the light will bounce back exactly along the same path (angle of reflection will also be 0 degrees).

These laws apply to all types of reflecting surfaces, including flat mirrors, curved spherical mirrors (concave/convex), and even rough surfaces.

The Two Laws of Reflection

  1. First Law: The incident ray (the incoming light), the reflected ray (the bouncing light), and the normal (an imaginary perpendicular line drawn at the point of contact) all lie in the exact same flat plane.
  2. Second Law: The Angle of Incidence (∠i) is always mathematically exactly equal to the Angle of Reflection (∠r). (Formula: ∠i = ∠r)

Key Terms Defined

  • Incident Ray: The ray of light directly approaching the mirror.
  • Reflected Ray: The ray of light bouncing off the mirror.
  • Normal: A 90-degree imaginary vertical line drawn exactly where the light hits the mirror.
  • Angle of Incidence (i): The angle measured between the incident ray and the Normal.
  • Angle of Reflection (r): The angle measured between the reflected ray and the Normal.

Questions and Answers

What is Diffuse Reflection?+

When light hits a rough surface (like a wall), the rays reflect in many different random directions. This is diffuse reflection. However, at every microscopic point, the Laws of Reflection are still strictly obeyed.

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