CBSE Geography Notes - Geography Ebooks | TheGeoecologist

Question 1

What is the standard meridian for Indian Standard Time and why was it chosen?

Accepted Answer

The standard meridian for Indian Standard Time is 82.5°E, passing through Mirzapur, Uttar Pradesh. It was chosen because it lies roughly central to India's longitudinal extent (68°7'E to 97°25'E), minimizing the maximum time difference within the country to about 1 hour 45 minutes.

Question 2

How do you calculate time difference between two longitudes?

Accepted Answer

Calculate the longitudinal difference in degrees, then multiply by 4 minutes per degree. For example, difference between 30°E and 60°W = 90°. Time difference = 90 × 4 = 360 minutes = 6 hours. Add time if moving east, subtract if moving west.

Question 3

What happens when you cross the International Date Line eastward vs westward?

Accepted Answer

Crossing the International Date Line eastward (toward America) subtracts one calendar day. Crossing westward (toward Asia) adds one calendar day. The time of day remains the same, only the date changes.

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