Reflection of Light (Concise Notes)

Visibility of an object
- An object is visible if it is itself a source of light or if it reflects light falling on it.
- A suitable instrument like eye to observe those light
How light travels
- Light moves in straight line, rectilinear path (Ray of Light)
  - the collection of ray is beam
- When encounters an object, a beam of light undergoes
  - reflection or
  - refraction or
  - both
Image – Visual replica of an object
- Real image – light actually come from
- Virtual image – light appears to come from

Laws of reflection
- First law: angle of incidence = angle of reflection, \(\angle i = \angle r\)
- second law: Incident ray, reflected ray and normal at the point of incidence are coplanar
- Equally applies to plane as well as curved surface
- Numerical
Types of Reflection
- Regular reflection – Most of the parallel light are reflected in parallel manner, in the same direction, by smooth surface. Polished/Reflective surfaces are responsible for such reflection.
- Diffusion – Parallel rays of light are reflected in varying directions, in irregular ways. Unpolished surfaces or rough surfaces are responsible for diffusion.

A flat surface that is smooth and reflects light.
Image formation by Plane mirror (Ray diagram)
- Point light – a source of infinite light rays. All follow laws of reflection.
- at least two such rays needed
Features of image formed by plane mirror (can be proved on the basis of Congruence of triangles)
- Virtual and behind the mirror
- Erect
- Same in size
- At the same distance
- Laterally inverted
Numerical