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### Course: Physics archive>Unit 10

Lesson 3: Measuring magnetic fields

# Earth's magnetic field (how to measure)

How can we describe the strength of the Earth's magnetic field using a magnet and a compass? What does this tell us? Created by Brit Cruise.

## Want to join the conversation?

• earth north is at 0 degrees, the magnet is put at 90 degrees to that. So 45 degrees is half way between them which means both fields are equal?

What does that tell me?
• Using this information, you can say something about the distance between the hand-held magnet and the compass in regards to the strength of the magnet, compared to the strength of the Earth's magnetic field - which, for all intents and purposes, is constant here.

If we had more information, we could write a formula using the distance and the angles to possibly come up with a numerical value for how strong the magnetic is, at least relative to the Earth's field.
• I didn't understand the idea?
• When the compass is at 0 degrees, the magnet has no apparent effect on the compass, which characteristically points North, to align with Earth's field. When the magnet is tipped into action, then moved closer to the compass, the compass begins to align with the magnet's field. When the compass is at 45 degrees, the compass has aligned equally with the two fields. When the magnet is this close, Earth's field is just as strong. We can See Earth's field is about as strong, in Brit's Super Observation Chamber, as a small magnet a few cm away from the videographer. This is so strong that many living organisms can use it for navigation.
• Could we implement a trigonometric function? I have a gut feeling that it works out somehow, but I can't pinpoint how. I'l keep trying.
• well for one thing 1) the earth's magnetic field is made completely out of pure energy both magnetic & electrical.
2) And this field of magnetic energy is created by the earth's core by the molten iron alloys that is contained in the outer core .
3) And we already know that the strength of the magnetic field so great that it continues to repel & protect all life on earth from the solar winds of the sun that are carried by the space winds in space along with other dangerous forces in space that we know & don't know about
4) As for the the north & south poles you might say these two different contents that exist in two different locations on earth are like two giant Tesla towers on the inside of a Tesla reactor that create & amplify energy in both effort & endurance.
5) As a result this also tells us that The Magnetic North Pole wanders, but slowly enough that a simple compass remains useful for navigation. At random intervals (averaging several hundred thousand years) the Earth's field reverses (the north and south geomagnetic poles change places with each other). These reversals leave a record in rocks that allow paleomagnetists to calculate past motions of continents and ocean floors as a result of plate tectonics.

The region above the ionosphere, and extending several tens of thousands of kilometers into space, is called the magnetosphere. This region protects the Earth from cosmic rays that would strip away the upper atmosphere, including the ozone layer that protects the earth from harmful ultraviolet radiation
• why mark 45? because on the half of the comepass it is 45 and that is the magnetic's place of where it is.
• is the video supposed to be muted?
• Is earth a natural magnet or an electromagnet?
(1 vote)
• Who was acting this and where?
(1 vote)
• Why is it 45° and not 30°, because sin(30)=0.5 which would be the half?
(1 vote)
• No, 30 is 1/3 of 90. Halfway between 0 and 90 would be 45. Good thinking though.
(1 vote)
• is it possible that 45 degrees is how the equinox points is set? (canser and capricorn) whit tought for the larger picture ?
(1 vote)
• Are this video can also describe measuring the magnet's field strength?
(1 vote)