Is the Earth's Magnetic Field strong and does it fluctuate a lot

Tags: earth, magnetic flux, magnetic induction, magnetism, physics
PPERERA is offline
Apr17-13, 04:41 PM
P: 2
I recently learned about Magnetism in my high school Physics class, and it made me think of all the applications there are for it. I was especially interested in magnetic induction. I understand that it is dependent on magnetic flux or the movement of the conductor.

I'm obviously not an expert on this topic, but it got me thinking: what if the Earth's magnetic field fluctuates? (My main reason for thinking that it does is that the core that produces is it is molten and always shifting, and there is scientific proof that the poles of the Earth's magnetic field shift.) If it does fluctuate, I believe we have a perfectly good resource that we could use to generate clean electricity.

P.S. - I did talk to my teacher, and she speculated that because our Earth had been in existence for a very long time, the magnetic field produced by the core has had enough time to form and settle and therefore would not fluctuate?
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mikeph is online now
Apr17-13, 06:15 PM
P: 1,200
There are fluctuations, but they are small. Over seconds, it's about ~ 100pT, when the absolute field is somewhere around 50 uT. During a solar flare the surface value might change by up to a few uT if you measure it in the right direction.

If you can predict it then I think you can orient a current loop in the right way and find a measurable voltage, but I think the induced current will be absolutely tiny- bigger loops mean bigger integrated flux variation (more inductance) but then you have more resistance in the wire too. And the short-term variations in the magnetic field are, to all intents and purposes, random- they're mostly coming from currents far away in the ionosphere, which are driven by wind and tidal forces (unpredictable). So your current is not going to be anything resembling AC or DC from which you might easily extract energy.
PPERERA is offline
Apr17-13, 07:48 PM
P: 2
Thanks for the response. I am that much more knowledgeable for it.

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