Detecting a Magnetic Field: Difference between revisions
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<math>B_{wire}=B_{earth} tan(\theta)</math> | <math>B_{wire}=B_{earth} tan(\theta)</math> | ||
<math>B_{wire}= 2 ✕ 10^{-5} tesla ✕ tan(18)</math> | <math>B_{wire}= 2 ✕ 10^{-5} tesla ✕ tan(18)</math> | ||
<math>B_{wire}= 6.49✕ 10^{-6} Tesla </math> | <math>B_{wire}= 6.49✕ 10^{-6} Tesla </math> | ||
Revision as of 13:43, 13 November 2015
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.
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
Be sure to show all steps in your solution and include diagrams whenever possible
Simple
Problem 17XP.003 from Matter and Interactions Book:
A current-carrying wire oriented north-south and laid over a compass deflects the compass 18° to the east. What is the magnitude of the magnetic field made by the current? The horizontal component of Earth's magnetic field is about [math]\displaystyle{ 2 ✕ 10^{-5} tesla }[/math] .
[math]\displaystyle{ B_{wire}=B_{earth} tan(\theta) }[/math]
[math]\displaystyle{ B_{wire}= 2 ✕ 10^{-5} tesla ✕ tan(18) }[/math]
[math]\displaystyle{ B_{wire}= 6.49✕ 10^{-6} Tesla }[/math]
Middling
Difficult
Connectedness
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- How is it connected to your major?
- Is there an interesting industrial application?
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
Books, Articles or other print media on this topic
External links
References
Chabay, R. & Sherwood, B. (2015). Matter and Interactions(4th Ed)(Vol 2). North Carolina: John Wiley & Sons,Inc.