6th CBSE Notes On Time and Time Zones

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  Grade : VI 

Geography  Chapter : 4 

    Time And Time Zones   

Short answer questions

Que: What is meant by Meridian?

The word meridian is derived from the Latin word meridianus, which means midday. Thus, meridian indicates the position of the sun at midday or noon.

Que: Why do we need a standard time?

We need a standard time to avoid confusion caused by the local time, which varies with longitude.

Que: Which city does the standard meridian pass through in India?

The Standard Meridian of India is 82°30’ E longitude. It passes through Mirzapur near Allahabad.

Que: Where is International Date Line located?

The International Date Line passes through the Mid-Pacific Ocean, including some islands. 

Que: Write few problems if we follow our local time. 

If the people follow our local time,

We may miss to watch live telecast.

We need to adjust our timing when we travel.

We may miss aero plane, train for our journey.

We may miss to attend any important interview.

Que: Why do many countries have more than one standard time?

Some countries like Canada, USA, Russia etc have more than one standard time because they have a large longitudinal extent with large geographical area.

Long answer questions

Que: Difference between Local time and Standard Time

Local Time Standard Time
The local time is the time of a particular meridian The standard time is the time officially adopted and followed by a country
It is calculated by the shadow cast by the sun at a particular place It is calculated by the time on the standard meridian
It changes with longitude It remains same in different longitudes of the country

Que: How many time zones are there in the world? How are they determined?
  • The earth has 24 time zones. 
  • As the earth takes 24 hours to complete one rotation, 24 time zones are marked at the interval of 15° longitudes. 
  • At some places, time zones have been adjusted to avoid division of a country into different time zones. 
  • France, USA, Russia, Canada, Australia and Brazil are a few countries that have more than one time zone. 
  • Each time zone has its own standard time. 
  • Hence, the watch needs to be adjusted while travelling to another time zone.
Que: Explain the significance of the International Date Line.
  • The International Date Line is 180° E and W longitude, where a new day starts and the old day ends. 
  • This line functions as a line of demarcation between two consecutive calendar dates. 
  • It is found in the Pacific Ocean. 
  • It is a zigzag line that keeps the island groups on either side. 
  • When we cross this line from west to east, we adjust our watches by adding a day, and when we cross it from east to west, we deduct a day

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