India is a large country. It covers a long range of longitudes (67°E to 97°E). As we know that variation in time is caused by longitudinal difference, so the time difference between the western-most and the eastern-most longitudes of India should be very large. For example, the time of Arunachal Pradesh should be two hours ahead of Gujarat, but such a situation could cause inconvenience in the activities like transmission of information across different parts of the same country.
To avoid this, we designate the 82°30 E longitude as Standard Meridian. The time at this longitude is accepted all across India as the Indian Standard Time.
