From the longitudinal extent of India it is observed that the longitudinal expanse is about 30o from west to east. This means that there would be a time-lag of two hours approximately from Gujarat to Arunachal Pradesh. To avoid such differences in local time, Indian standard time has been fixed to give the whole country a uniform time. The local time of the Standard Meridian of 82o30’E is observed as the Standard Time by the whole country. Because of this reason we find that the sun rises two hours earlier in Arunachal Pradesh as compared to Gujarat in the west but the watches show the same time.
