Question

What is local time? Estimate the time at the following longitudes assuming the Greenwich mean 10 as 10 am.
(i) 45 degree East longitude
(ii) 30 degree West longitude

Answer 1

Hint: A time zone is a region that has a common uniform time for social, legal, and commercial convenience. Greenwich Mean Time (GMT) refers to the average solar time at the Royal Observatory in Greenwich, London, which became adopted as a global time standard.

Complete answer: the time with respect to the meridian through a specific place, in contrast to that of the time zone within which the place is located, the time in a specific place as compared to that of another place to the east or west is called the local time.
To calculate the time at the following longitudes, we must consider that as we go 1 degree towards east or west from the prime meridian, 4 minutes are added or subtracted from the time respectively.
(i) 45 degree Eas
45*4 = 180 minutes
= 3 hours
Therefore the time will be 10 am + 3 hours, i.e. 1 pm.
(ii) 30 degree West
30*4 = 120 minutes
= 2 hours

Therefore the time will be 10 am - 2 hours, i.e. 8 am.

Note: The world is divided longitudinally into time zones, with an hour’s difference roughly 15 degrees apart. There are 24 time zones in the world, and some countries have more than 2 time zones. There are 23 countries with at least 2 time zones.