When it is 12 noon by Indian Standard Time, what is the time at Greenwich?
- A.5:30 am
- B.6:30 am
- C.5:30 pm
- D.6:30 pm
Correct answer
Explanation
The correct answer is B, 6:30 in the morning. Indian Standard Time is the local time of 82 degrees 30 minutes east. Multiplying 82.5 degrees by four minutes gives 330 minutes, that is five hours and thirty minutes, and since India lies east of Greenwich its clock is ahead by that much. Subtracting five and a half hours from 12 noon leaves 6:30 am.
Option A, 5:30 am, would follow from an offset of six and a half hours, which belongs to no Indian meridian. Options C and D place Greenwich ahead of India, reversing the rule that places to the east see the sun first and therefore run ahead. The direction is the part most often lost in the exam hall, so fix it with a simple sentence: east is ahead, west is behind. The same calculation in reverse tells you that noon at Greenwich is 5:30 in the evening in India.
Read the full article: Latitudes, Longitudes and Time: Grid, IST and Date Line
Practice Questions
View allIndian Standard Time is based on which meridian?
- A.75 degrees east
- B.82 degrees 30 minutes east
- C.88 degrees 30 minutes east
- D.90 degrees east
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This meridian passes near Mirzapur in Uttar Pradesh and runs roughly through the middle of the country, so it was adopted as the standard meridian of India.
Read the full explanation →One degree of longitude corresponds to how much difference in time?
- A.One minute
- B.Four minutes
- C.Fifteen minutes
- D.One hour
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The earth completes one rotation of 360 degrees in 24 hours, that is 1,440 minutes, and dividing 1,440 by 360 gives four minutes for every degree of longitude.
Read the full explanation →The Tropic of Cancer does not pass through which of the following Indian states?
- A.Jharkhand
- B.Chhattisgarh
- C.Odisha
- D.Tripura
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The Tropic of Cancer passes through eight states, namely Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram.
Read the full explanation →Which is the only parallel of latitude that is a great circle?
- A.The equator
- B.The Tropic of Cancer
- C.The Arctic Circle
- D.The Tropic of Capricorn
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A great circle is one whose plane passes through the centre of the sphere and which therefore divides it into two equal halves.
Read the full explanation →The Prime Meridian passes through which place?
- A.Paris
- B.Greenwich
- C.Rome
- D.Washington
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The meridian running through it was accepted as the zero meridian, from which all longitudes are counted east and west, and its local time is Greenwich Mean Time, the reference for the world's standard times.
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