Explanation: India, being a large country, spans a significant longitudinal extent from east to west. This longitudinal span results in a natural time difference between the eastern and western parts of the country. The easternmost part of India, Arunachal Pradesh, experiences daylight earlier than the westernmost part, Gujarat. This difference in the timing of sunrise and sunset leads to a time difference of approximately two hours between these two regions.
To manage this time difference, India has adopted a standard time, known as Indian Standard Time (IST), which is based on the longitude passing through the city of Allahabad (now Prayagraj). This standard time is set at 82.5°E longitude, which is close to the center of the country. By adopting a single standard time, India avoids the complexity of having multiple time zones, which would be necessary if each region were to follow its local time.
The concept of time zones is based on the Earth's rotation and the fact that the sun rises and sets at different times across different longitudes. As the Earth rotates, different parts of the planet face the sun at different times, leading to a natural time difference. This is why the east-west extent of a country is the primary factor in determining the time difference between its eastern and western parts.
In summary, the time lag of two hours between Gujarat and Arunachal Pradesh is due to the longitudinal extent of India from east to west. This natural time difference is managed by adopting a standard time for the entire country, which is based on a specific longitude. Understanding this concept is crucial for comprehending how time zones work and how they are managed in large countries like India.