Mirrors

A mirror is an object that reflects an image. In order to understand mirrors we need to understand what an image is. Generally when someone refers to an image they are probably referring to a two dimensional image such as a painting or photo or three dimensional images such and carvings and sculputres. However in the field of optics, image refers specifically to reproduction of an object formed by light waves coming from the object.

History

Natural mirrors such as the surface of water have existed since prehistoric times, but humans have been making artificial mirrors for a long time as well using various materials like stone, metal and glass. Modern mirrors are made by coating a thin metallic layer on glass. Silver and aluminium are commonly used due to their high reflectivity. Glass is used because it is a naturally smooth and hard surface which is transparent to light waves.