Question

The sun rises two hours earlier in Arunachal Pradesh as compared to Gujarat in the west but the watches show the same time. How does this happen?

Answer 1

Hint: The earth's surface is divided into 24 time zones of one hour each. Each zone thus covers 15 degrees of longitude and every longitude differs by 4 minutes.

Complete answer: The earth’s globe consists of 360 meridians and it is divided into two sections. Meridians ranging from 1-180 are referred to as the Eastern Meridians and the meridians ranging from 181-360 are referred to as Western Meridians. In India, the longitude of 82.30 degrees East is treated as the standard meridian. This is because the meridian 82.30 passes through Mirzapur so, for the whole country, the local time at this meridian is taken as the standard time and is known as the Indian Standard Time (IST). There is a difference in the local times of Gujarat and Arunachal Pradesh. The difference between these two states is 2 hours. So because of this reason, it is important to adopt the local time of some central meridian of a country as the standard time for the country in order to avoid chaos and confusion. Hence, the watches show the same time in both Arunachal Pradesh and Gujarat.

Note: As the earth revolves from west to east, those places lying to the west of Greenwich will be behind Greenwich time and those to the east will be ahead of it. The Indian Standard Time is 5 and a half hours ahead of the Greenwich Mean Time.