Question

why is 82 degree 30 degree east selected as Standard Meridian of India

Answer 1

The longitudinal extent of India is 30 degrees. The sun rises in the east and sets in the west. It takes 4 minutes for the sun to move across 1 longitude. Thus the eastern most point of India would be 2 hours ahead of the western most point (30X4=120 minutes) , in accordance with the local time. This difference in time might create a lot of confusion in air, rail timings and so many other things. To avoid this confusion a longitude passing through the mid point of 68 degrees 7 minutes (western most longitude) and 97 degrees 25 minutes (eastern most longitude) is taken as the standard prime meridian of India. The time at the standard meridian 82 degrees 30 minutes which passes through Mirzapur in UP is taken as the standard time of India , followed all over the country.