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### Course: Physics archive>Unit 18

Lesson 3: Measuring magnetic fields

# Measure the Earth's field!

You can use a bar magnet and a compass to get a rough idea of the strength of Earth's magnetic field

### What happened?

The force on a compass due to the Earth's magnetic field is relatively weak. Think of it as a gentle magnetic breeze.
However the field near the household magnet is dense like a tornado. Strong near the magnet and very weak as you move away.

## Challenge 1: How strong is the Earth's magnetic field?

Find (or make) a compass & 1 household magnet.
Can you determine the exact distance at which the household magnet force equals that due to the Earth's magnetic field?
What does this distance tell us?

## Want to join the conversation?

• Is there a way to measure magnetivity? How would you measure something like that?
(3 votes)
• Yes, you can do it with Teslameter. It´s relatively expensive apparatus or cheep (free) application on mobile. :-)
(2 votes)
• What are the materials that i can use to make a compass & one household magnet.
(2 votes)
• magnet that attract is northpole and sorthpole and the one that replling are northpole and northpole and sorthpole and sorthpole
(2 votes)
• How does the Earth creates magnetic field around it?
(2 votes)
• i liked to play with magnets alot when i was little
(1 vote)
• so do i its because of the gravity on the earth!
(2 votes)
• Would this distance be pretty big, because of the size of the Earth.
(1 vote)
• Yes, but because of the mass and density of the of the Earth. Not exactly the size.
(1 vote)
• How can the north and south poles effect a compass
(1 vote)
• Well, isn't a household magnet stronger than the earth's magnetic field? The earth's mag field strength is .000005 tesla and a refrigerator magnet is .005 tesla?
(1 vote)
• what is the circumference of the the earth? explain
(1 vote)
• How dose magnetism work?
(1 vote)
• It depends on the electron configuration of the material. It is now possible to design materials that have magnetic properties from non-magnetic starting materials,

http://www.nanowerk.com/nanotechnology-news/newsid=40988.php
(1 vote)
• Why have a compass where 1 inch = 1 kilometer? That just does not sound reasonable.
(1 vote)
• That's an orienteering compass. That scale is for use on maps and doesn't have anything to do with the compass itself. It's just another useful tool to have on hand alongside the compass and map.
(1 vote)