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ICSE Class 9 Geography Question 18 of 22

Geographic Grid: Latitudes and Longitudes — Question 12

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12
Question

Question 3(d)

State with one practical example how is time of a place found with the help of longitudes.

Answer

As the earth takes 24 hours to make a complete rotation along its axis crossing 360° lines of longitude, so earth takes nearly 4 minutes to move 1° longitude.

For example, Indian Standard Time is based on 82 1/2° E longitude. So if the time in India is 12 noon, so it will be 6.30 A.M. in England or GMT.

The time difference between 0° and 82 1/2° E will be-
82.5 × 4 = 330 minutes or 330 ÷ 60 = 5 1/2 hours

So there is difference of 5 1/2 hours between India and England, as England lies in the west, so the time will be 5 1/2 hours less than India.