Previous Year Question
Which of the following longitudes is known as “Standard Meridian” in India?
87°30′ E
85°30′ E
84°30′ E
82°30′ E
Correct Answer: D
Detailed Solution
The Standard Meridian of India is 82°30′ E longitude. The local time along this longitude is adopted throughout the country as Indian Standard Time (IST).
This Standard Meridian passes near Mirzapur in Uttar Pradesh. India has an east-west longitudinal extent of nearly 30°, due to which there can be a difference of about two hours in local time between its eastern and western parts. A Standard Meridian is therefore used to maintain uniform time throughout the country.
For calculating time, 1° of longitude corresponds to 4 minutes. Therefore:
82°30′ = 82.5°
82.5 × 4 = 330 minutes = 5 hours 30 minutes
Hence, IST is 5 hours 30 minutes ahead of Greenwich Mean Time (GMT).