The sun rises two hours earlier in Arunachal Pradesh as compared to Gujarat. This causes a time lag of 2 hrs from Gujarat to Arunachal Pradesh to avoid confusion and to have a standard time for reference, The 82.30'Eastern Longitude has been taken as the standard time for the whole country.

Standard Meridian at 82 1/2 degree east

The Earth is divided into 360 degrees of longitude, and the prime meridian, located at 0 degrees, is used as the starting point for measuring longitude. However, countries and regions often choose their own standard meridian to suit their specific needs. In the case of India, the standard meridian is set at 82 1/2 degree east.

Reasons for choosing 82 1/2 degree east as the standard meridian:

Geographical Center:
- India is a vast country spanning from the Arabian Sea in the west to the Bay of Bengal in the east.
- The 82 1/2 degree east meridian is roughly the center of the country, making it a convenient point of reference for mapping and geographical purposes.

Uniform Time Zone:
- A standard meridian helps in determining the time zones across a country or region.
- By choosing 82 1/2 degree east as the standard meridian, India has established the Indian Standard Time (IST), which is followed uniformly across the country.
- IST is set at GMT+5:30, which means that the time in India is 5 hours and 30 minutes ahead of Greenwich Mean Time (GMT).
- Having a uniform time zone helps in maintaining consistency in various sectors such as transportation, communication, and administration.

Administrative Convenience:
- The choice of 82 1/2 degree east as the standard meridian also aligns with administrative convenience.
- India is a diverse country with multiple states and union territories.
- Setting the standard meridian in the middle of the country helps in minimizing the time difference between the eastern and western regions, making it easier to coordinate administrative functions.

Impact on Bordering Countries:
- The selection of the standard meridian also takes into consideration the neighboring countries.
- By choosing 82 1/2 degree east, India maintains a reasonable time difference with its neighboring countries, such as Pakistan, which follows Pakistan Standard Time (PST) at GMT+5.

In conclusion, the selection of 82 1/2 degree east as the standard meridian for India is based on geographical centrality, uniform time zone implementation, administrative convenience, and consideration of neighboring countries. This choice facilitates efficient coordination, mapping, and timekeeping across the diverse regions of India.