Reflection Of Light

Key Notes:

Definition of Reflection

• Reflection of light occurs when light rays strike a surface and bounce back into the same medium.

• The bouncing of light follows specific laws, known as the laws of reflection.

Laws of Reflection

First Law: The angle of incidence (i) is equal to the angle of reflection (r).

• θ_i = θ_r

Second Law: The incident ray, the reflected ray, and the normal to the surface at the point of incidence all lie in the same plane.

Types of Reflection

• Regular Reflection:
  • Occurs on smooth surfaces like mirrors.
  • Produces clear and sharp images.

• Diffuse Reflection:
  • Occurs on rough surfaces.
  • Scattered light results in no clear image.

Terms Related to Reflection

• Incident Ray: The light ray that strikes the surface.
• Reflected Ray: The light ray that bounces off the surface.
• Normal: A perpendicular line drawn to the surface at the point of incidence.
• Angle of Incidence: The angle between the incident ray and the normal.
• Angle of Reflection: The angle between the reflected ray and the normal.

Reflection in Plane Mirrors

• Image Characteristics:
  • Virtual and upright.
  • Same size as the object.
  • Laterally inverted (left-right reversal).
  • Appears to be at the same distance behind the mirror as the object is in front.

Applications of Reflection

• Used in periscopes, kaleidoscopes, and optical instruments.

• Helps in the working of mirrors in vehicles and household applications.

Multiple Reflections

• When light reflects multiple times between two mirrors, it forms multiple images.

• The number of images formed depends on the angle between the mirrors.

Real-Life Examples

• Reflection on calm water surfaces.

• Mirrors in dressing rooms and cars.

• Optical devices like telescopes and microscopes.