Chapter Summary
Bouncing of light from a shiny surface is called reflection of light.
Mirrors form image because of reflection of light.
Angle of reflection is equal to angle of incidence.
Incident ray, reflected ray and normal at the point of incidence all lie in the same plane.
A mirror, that is part of a sphere, is called spherical mirror. There are two types:
Concave Mirror: Reflective surface inside sphere
Convex Mirror: Reflective surface outside sphere
When rays of light coming from infinity are reflected by concave mirror, all the reflected rays converge at focus.
So, a concave mirror is also called a converging mirror.
When rays of light coming from infinity are reflected by convex mirror, all the reflected rays appear to diverge from focus.
So, a convex mirror is also called a diverging mirror.
Most of the images formed by concave mirror are real and inverted.
When object is between F and P then virtual and erect image is formed by concave mirror.
All the images formed by convex mirror are virtual, erect and smaller than object.
When a ray of light enters one medium from another, there is deviation in its path. This deviation is called refraction of light.
Incident ray, refracted ray and normal at the point of incidence all lie in the same plane.
Ratio of sin of angle of incidence to sin of angle of refraction is constant for a given pair of media.
A reflective surface with at least one curved face is called lens. Following are the most commonly used lenses:
Convex Lens: Both surfaces are convex, also called converging lens.
Concave Lens: Both surfaces are concave, also called diverging lens.
Most of the images formed by convex lens are real and inverted.
When object is between F and O then virtual and erect image is formed by convex lens.
All the images formed by concave lens are virtual, erect and smaller than object.
Real Image: It can be obtained on screen.
Virtual Image: It cannot be obtained on screen.