Question

history of sherical mirrors in human civilization

Answer 1

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.   Spherical mirrors   Concave mirrors   Convex mirrors The invention of concave and convex mirrors led to many changes and have become a part of our life . 

The first mirrors used by people were most likely pools of dark, still water, or water collected in a primitive vessel of some sort. The earliest manufactured mirrors were pieces of polished stone such as obsidian, a naturally occurring volcanic glass. Examples of obsidian mirrors found in Anatolia (modern-day Turkey) have been dated to around 6000 BC. Mirrors of polished copper were crafted in Mesopotamia from 4000 BC, and in ancient Egypt from around 3000 BC. Polished stone mirrors from Central and South America date from around 2000 BC onwards. In China, bronze mirrors were manufactured from around 2000 BC,some of the earliest bronze and copper examples being produced by the Qijia culture. Mirrors made of other metal mixtures (alloys) such as copper and tin speculum metal may have also been produced in China and India.Mirrors of speculum metal or any precious metal were hard to produce and were only owned by the wealthy.

Answer 2

Answer:

(i) The earliest manufactured mirrors were pieces of polished stone such as obsidian, a naturally occurring volcanic glass.

(ii) They are from around 6,000 B.C. Mirrors of Copper (Cu) were crafted in Mesopotamia.

(iii) Bronze mirrors were manufactured from around 2,000 B.C. Mirrors made of mixtures such as Copper and tin speculum metal are also been produced in China and India.

(iv) Metal coated glass mirrors are said to have been invented in Sidon in first century A.D. and glass mirrors backed with Gold leaf were used by Romans.

(v) Ptolemy conducted number of experiments with curved polished Iron mirrors.

(vi) China people began making mirrors with the use of Silver Mercury amalgams as early as superior method of coating glass with tin Mercury amalgam.

(vii) The invention of the silvered glass mirror is credited to German.

(viii) This silvering process was adopted for mass manufacturing and led to the greater availability of affordable mirrors.

(ix) Now-a-days, Mirrors are decomposition directly on the glass substrate.