Model Question and Answers for APSC | The sun rises two hours earlier in Arunachal Pradesh as compared to Gujarat in the west, but watches show the same time. Explain the fact.
Ans: Earth is divided into 360 vertical lines known as longitudes and a shift in every longitude gives a time difference of four minutes. Every 15 degree shift (longitudinal shift) results in a time difference of one hour. The longitudinal difference between India’s easternmost point Kibithu in Arunachal Pradesh and the westernmost point in Gugariyana, Gujarat is almost 30 degrees — a time difference of two hours.
However in the event of a single time zone, like in India, with the country spread over areas wider than the one hour mark, some areas see early sunrise and sunset and the opposite extreme ends see them late. But since the time zone is one, watches show the same time everywhere.
Indian Standard Time (IST) represents the time observed throughout India. Indian Standard Time is calculated on the basis of 82.5° E longitude, just west of the town of Mirzapur, near Allahabad in the state of Uttar Pradesh.