If it is 10:00 a.m. at Greenwich Mean Time (GMT), then what will be th

If it is 10:00 a.m. at Greenwich Mean Time (GMT), then what will be the time at 90° E longitude?

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5:00 a.m.

4:00 a.m.

3:00 p.m.

4:00 p.m.

Answer is Right!

Answer is Wrong!

This question was previously asked in

UPSC CDS-1 – 2023

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The Earth rotates 360 degrees in 24 hours. This means it rotates 15 degrees in one hour (360/24 = 15), or 1 degree every 4 minutes (60/15 = 4). Longitudes to the east of GMT are ahead in time, and longitudes to the west are behind. The difference in longitude between GMT (0°) and 90° E is 90°. The time difference is (90/15) hours = 6 hours. Since 90° E is east of GMT, the time will be 6 hours ahead of GMT. If it is 10:00 a.m. at GMT, then at 90° E, the time will be 10:00 a.m. + 6 hours = 4:00 p.m.

For every 15 degrees of longitude, there is a time difference of one hour. Eastward travel adds time, while westward travel subtracts time.

GMT (Greenwich Mean Time) or UTC (Coordinated Universal Time) is the standard time at the prime meridian (0° longitude). India’s standard time (IST) is 5.5 hours ahead of GMT, corresponding to 82.5° E longitude (82.5 * 4 minutes = 330 minutes = 5 hours 30 minutes).

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