Question 8 of 10intermediate💡 UnderstandEssay4 marks

What is the difference between local time and standard time? Discuss it in groups, with each group writing an answer in 100 to 150 words. Compare the answers.

Correct Answer

Local time is the time determined by the actual longitude of a specific place on Earth.

Since the Earth rotates 360° in 24 hours, every 15° of longitude corresponds to a 1-hour time difference. Therefore, places at different longitudes have different local times — eastern places have earlier local times than western places.

Standard time, on the other hand, is a uniform time adopted by a country for practical convenience. Instead of using different local times across a country, one central meridian is chosen as the reference.

In India, the standard meridian at 82.5°E determines Indian Standard Time (IST), which is 5 hours 30 minutes ahead of Greenwich Mean Time. All of India follows IST regardless of the actual local time at any particular location.

This uniformity simplifies transportation schedules, communication, and administration across the country.

Exercise: Questions, activities and projects | Q: 5 | (Page Page 24)
For More Understanding

Explanation

The chapter explains that local time varies with longitude — each place has its own local time based on when the sun is highest in the sky at that location. However, using different local times within a country would cause confusion in daily life, transportation, and communication. Therefore, countries adopt a standard time based on a central meridian. India uses the 82.5°E meridian as its standard, making IST uniform across the country. The discussion format encourages students to articulate the distinction clearly and learn from comparing different group answers.

Solution Steps

  1. Local time is determined by the actual longitude of a specific place on Earth

  2. Every 15° of longitude corresponds to a 1-hour time difference due to Earth's rotation

  3. Eastern places have earlier local times than western places

  4. Standard time is a uniform time adopted by a country for practical convenience

  5. A central meridian is chosen as the reference for standard time

  6. India uses the 82.5°E meridian as its standard, making IST uniform across the country

  7. Uniformity simplifies transportation, communication, and administration

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