How is the time difference between two cities is calculated?
Thr earth rotates one full circle in 24 hours and one complete rotation of earth means that it has gone over 360 degrees and the degrees are marked by longitudes with zero degree line passing through Greenwich village on the banks of river Thames near London. 24 hours represents 24 x 60 minutes = 1440 minutes. therefore difference of time between 2 longitudes is 1440/360 = 4 minutes. If we know the longitudes of 2 places, time difference between them will be (4 minutes) x (difference in longitudes). If the difference in longitudes between two places is 180 degrees, then the time difference is 180 x 4 = 720 minutes or 12 hours, which roughly represents time difference between India & America.
