Page 2 - Lesson Notes
P. 2

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                    To avoid time confusion within a large country and throughout world the
                      concept of time zone was introduced.
                  
                    World is divided into 24 time zones of an hour each.

                    Each zone covers 15° of longitude.
                  
                    Again the a standard time is chosen for a particular time zone by taking
                    local time of a central meridian within that time zone.
                  
                    Starting from 0° meridian GMT at London to reach 180° meridian the
                    difference of time becomes almost one day.
                  
                    Hence we have International Date line running along 180° meridian.
                  
                    If someone crosses this line from east to west lose a day while if he
                      crosses from west to East he gains one day.
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