Question

How many degrees of longitude does each time zone cover?

• A. 15
• B. 30
• C. 60
• D. 180

Hint:

1 hour = 15° rotation of Earth → each time zone spans 15° longitude.

Answer 1

The Correct Option is A

To determine how many degrees of longitude each time zone covers, let's examine the relationship between Earth's rotation and time measurement:

1. Earth's Rotation Basics:
The Earth completes one full 360° rotation about its axis every 24 hours. This rotation is what creates day and night cycles.

2. Calculating Degrees per Hour:
To divide the 360° rotation into 24 equal time segments:

• Total rotation: 360°
• Total hours in day: 24
• Degrees per hour: 360° ÷ 24 = 15°

This means the Earth rotates 15° of longitude each hour.

3. Time Zone Implementation:
The international time zone system follows this 15° principle:

• Each time zone spans approximately 15° of longitude
• Adjacent time zones are 1 hour apart
• The Prime Meridian (0°) at Greenwich, England serves as reference

4. Practical Considerations:
While the system is based on 15° increments:

• Actual time zone boundaries often follow political borders
• Some large countries use single time zones despite spanning >15°
• Certain regions use half-hour or quarter-hour offsets

5. Why Other Options Are Incorrect:
- 30° would mean only 12 time zones (too few for practical use) - 60° would mean just 6 time zones (extremely imprecise) - 180° would create only 2 time zones (completely impractical)

Final Answer:
Each standard time zone covers 15 degrees of longitude.