The tendency of incident light rays to follow these rules is increased for lenses that are thin. For such thin lenses, the path of the light through the lens itself contributes very little to the overall change in the direction of the light rays. We will use this so-called thin-lens approximation in this unit.
Hindi got its name from the Persian word Hind, meaning 'land of the Indus River'. Persian speaking Turks who invaded Punjab and Gangetic plains in the early 11th century named the language of the region Hindi, 'language of the land of the Indus River'.
By Irene Thompson | Updated July 22, 2014 by Irene Thompson. NamaskÄr â Welcome. Hindi, also known as Khadi Boli, Khari Boli, belongs to the Indo-Aryan branch of the Indo-European language family. It is spoken as a first language primarily in northern and central India by more than 258 million people (Ethnologue).