Light is a form of energy which travels as electromagnetic waves; it is the form of energy which produces the sensation of sight. The branch of physics that deals with the properties and applications of light is called optics. Microscopes, telescopes, binoculars, cameras and projectors are optical instruments used in educational, scientific and entertainment fields. This chapter covers reflection (plane and spherical mirrors), refraction and total internal reflection.
1. Reflection of Light
Light falling on any polished surface, such as a mirror, is reflected. For a plane mirror MM′ with a ray AO striking it at O:
- Incident ray – the ray AO falling on the mirror.
- Reflected ray – the ray OB sent back by the mirror.
- Normal – the line ON drawn at O perpendicular to the mirror.
- Angle of incidence (i) – the angle made by the incident ray with the normal (angle AON).
- Angle of reflection (r) – the angle made by the reflected ray with the normal (angle NOB).