Light - Reflection and Refraction
Light is a form of energy which enables us to see objects.
Objects are visible to us due to reflection of light from the object and then falling on our eyes. Reflection of light is a phenomenon in which light, after falling on a surface, returns back into same medium. Image formation in mirrors is due to reflection of light. Mirrors can be classified as plain or spherical. Spherical mirrors are classified as concave mirror and convex mirror.
A highly polished surface will reflect most of the light falling on it, but there are material medium like glass and water which allow the light to pass through them or refract. Refraction of light is a phenomenon of bending of ray of light as it passes from one medium to another. On entering the medium, the direction in which ray of light bends depends upon optical density of pair of media. Refractive index of a material determines the amount of bending and optical density of medium.
Lenses refract the light falling on them. A lens is a transparent material bounded by two surfaces, of which one or both surfaces are spherical. There are two types of lenses, concave lens and convex lens.
Ray diagram, mirror formula and lens formula are used to find nature, size and position of image formed after reflection and refraction.