Why do we need a standard meridian for india ?
The time of a place depends on the longitude that passes through it. Therefore, the standard time for each country is usually taken as the time of the central meridian that passes through it. India has a vast longitudinal extent. Since many meridians pass through it, it is important to adopt the local time of one central meridian of a country as the standard time for the country. Thus, we need a standard meridian for the country. In India 82 ½ °E longitude determines the standard time. This is known as the Indian Standard Time. This longitude passes through Allahabad in Uttar Pradesh.