Light is a form of energy and it travels in a straight line. We can see things around us only when the light reflected by them reaches our eyes. This chapter covers spherical and parabolic mirrors, the images they form, the laws of reflection, multiple reflection (kaleidoscope and periscope), refraction, refractive index, Snell's laws and the dispersion of light.
1. Mirrors
A mirror is an optical device with a polished surface that reflects the light falling on it. A typical mirror is a glass sheet coated with aluminium or silver on one of its sides to produce an image.
- Mirrors have a plane or curved surface.
- Curved mirrors have surfaces that are spherical, cylindrical, parabolic and ellipsoid.
- The shape of a mirror determines the type of image it forms. Plane mirrors form the perfect image of an object, whereas curved mirrors produce images that are either enlarged or diminished.