Why is there a time difference of about 5 hours between India and London?

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Detailed Solution

The time difference of about 5 hours between India and London exists because of the Earth’s rotation and their different longitudes. India Standard Time (IST) is based on the 82.5° East meridian, while London time follows the Prime Meridian (0° longitude).

Since the Earth rotates 15 degrees every hour, this results in a 5 hours and 30 minutes difference between IST and UK time now (Greenwich Mean Time or GMT).

However, during British Summer Time (BST), when clocks are set one hour ahead in the UK (from March to October), the time difference becomes 4 hours and 30 minutes.

This means if it’s 12:00 PM in London time now, it’s 4:30 PM in India during summer, and 5:30 PM during winter. To know the current London time, always consider whether the UK is observing daylight saving.

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