Which statement is true about the Earth's magnetic field strength?

Which statement is true about the Earth's magnetic field strength?

• A. It ranges from 25 to 65 microteslas
• B. It is exactly 0.5 tesla
• C. It exceeds 1 tesla
• D. It is less than 1 microtesla

Answer: (A)

The Earth's magnetic field at the surface is a very weak field, measured in microteslas. Across the planet it varies, being stronger near the poles and weaker near the equator. Typical surface values fall in the range of about 25 microteslas up to about 65 microteslas. That makes the statement describing the field strength as roughly 25 to 65 microteslas the accurate one. Think of the other options in terms of scale: 0.5 tesla would be 500,000 microteslas—much larger than the Earth's field. A field exceeding 1 tesla is even stronger. Being less than 1 microtesla would be far smaller than what is observed in most places. So the tens of microteslas range correctly captures the real strength of Earth’s magnetic field at the surface.

The Earth's magnetic field at the surface is a very weak field, measured in microteslas. Across the planet it varies, being stronger near the poles and weaker near the equator. Typical surface values fall in the range of about 25 microteslas up to about 65 microteslas. That makes the statement describing the field strength as roughly 25 to 65 microteslas the accurate one.

Think of the other options in terms of scale: 0.5 tesla would be 500,000 microteslas—much larger than the Earth's field. A field exceeding 1 tesla is even stronger. Being less than 1 microtesla would be far smaller than what is observed in most places. So the tens of microteslas range correctly captures the real strength of Earth’s magnetic field at the surface.