Ray Optics and Optical Instruments – Notes

Ray optics-introduction
Electromagnetic radiation to which the human eye is sensitive is called “visible light”.
In terms of wavelength the range of visible light is 700nm to 400nm.
The study of different optical phenomena by treating light as rays is known as “ray optics”.
Laws of reflection:
• The angle of incidence is equal to the angle of reflection.
• The incident ray, the reflected ray and the normal to the surface at the point of incidence all lie in the same plane.
When light rays from an object, after reflection or refraction, actually meet at a point and form an image it is called a “real image”.
If light rays, after reflection or refraction, appear to diverge from a point the image is called a “virtual image”.

Spherical mirrors- ray diagrams
If the convex side is given a silver coating and this concave surface acts as a reflecting surface the mirror is called a “concave mirror”.
If the concave surface is coated in silver and the smooth convex surface acts as a reflecting surface the mirror is called a “convex mirror”.