Earlier still or dark water
collected in a vessel was considered or used as mirrors by ancient people. Then
as days passed obsidian mirrors came in to existence followed by metal coated
glass mirrors this led to discovery of metal coated spherical or parabolic
mirrors. A spherical mirror is a mirror which has the
shape of a piece cut out of a spherical surface. There are two types of
spherical mirrors: concave, and convex. These mirrors are also known
as parabolic mirrors discovered in mid9th century Ibn al haytham and Ibn
sahl.parabolic mirrors were described in classical antiquity written by
mathematician-Diocles . In addition to these researches Ptolemy also carried
out experiments with curved polished iron mirrors and discussed about convex
spherical and concave spherical mirrors in his book optics.
Inspite of these researches finding the focal
length of spherical mirror was a though task but finally Ibn al Hay tham got a
break through by finding out the focal length of curved surfaces using the laws
of reflection.he stated that “All the
reflected rays of a mirror converge or diverge and meet at a point known as
focus and the distance between focus and pole of mirror is known as focal point
of mirror.’’Also many scientists came to a conclusion that spherical
mirrors can be divided into concave and convex mirrors.
invention of concave and convex mirrors led to many changes and have become a
part of our life .