Detecting a Magnetic Field

Short Description of Topic

The Main Idea

A compass can be used to determine the magnetic field in a wire. If a compass is not in the proximity of any iron or steel object, the compass will naturally point in the direction of the Earth's magnetic north pole. If a current carrying wire is brought near the compass, the compass needle will deflect in the direction of the net magnetic field.

This shows the Magnetic Field around a wire. The field above and below are in opposite directions which Oerested determined.

A Mathematical Model

A useful attribute of a compass is that you can calculate the the magnetic field of current carrying wire when you figure out the deflection angle. This equation is: [math]\displaystyle{ B_{wire}=B_{earth} tan(\theta) }[/math] where [math]\displaystyle{ \theta }[/math] is the deflection angle, [math]\displaystyle{ B_{earth} }[/math] is the earth's magnetic field which is a constant value of 2e-5 Tesla.

A Computational Model

How do we visualize or predict using this topic. Consider embedding some vpython code here Teach hands-on with GlowScript

Examples

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Connectedness

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History

This phenomenon was discovered by Danish scientist, Hans Oersted in 1826. After stumbling upon the deflection of a needle, he further investigated the math behind the event. He discovered that the magnitude of the magnetic field depends on the amount of current; if there is no current there will be no magnetic field. He also discovered that the deflection direction of the compass when the wire is above the wire is opposite the deflection direction when the wire is below the wire. This was the start of understanding magnetic fields.

See also

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Further reading

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External links

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References

Chabay, R. & Sherwood, B. (2015). Matter and Interactions(4th Ed)(Vol 2). North Carolina: John Wiley & Sons,Inc.