What is the purpose of having time zones?nWhy is standard time needed for every country?nFor every degree of longitude the time difference is 4 min. Explain?nHow does the time of a place depend on its longitude?
- Due to the rotation of the earth the time differes in different places. To standardize the time of different places of the earth and prevent confusion during long travels, the earth was divided into time zones. This was done by creating time zones that expanded to 15 degrees of longitude. Each zone is an hour different from its neighboring time zones, with a total of 24 time zones corresponding to the 24 hours in a day.
- Around the earth there are 360 longitudes. Each longitude has 4 minutes time difference. As we move to the east we see time advancing. In countries with large longitudinal extent there can can be several longitudes passing through the country.To have a fixed time all over the country, the central longitude's time is considered to be the country's standard time.This time is called the standard time.
- It has to be understood that due to Earth's rotaion not all spots on the earth receive direct Sun rays at one particular time. It has been seen that for every longitude the time of the direct rays of Sun differes by 4 mins. Thus as we move rtight we add 4mins and as we move left we deduct 4mins.
- The previous point also explains how time depends on longitude. Refer to the previous point.