[chris (OP)]

Roy says:

I placed a magnetic compass on top of my plasma ball. Now the compass needle is reversed. Should this happen? If so, could a plasma discharge from the sun reverse the Earth's magnetic field instantly?

What does everyone think?

[yor_on]

If the sun would go Nova you mean? Don't know how strong that Plasma discharge would have to be, but my guess is that it needs to be pretty da**ed strong for that. The reason we have pole reversals is coupled to the Earths core consisting of solid iron. that iron is in its turn surrounded by a melted liquid of metal moving inside. The flow of that creates electric currents which in its turn create a magnetic field. As it moves around the magnetic field adapts. And I don't think our sun can go nova, the mass is to small.

[chris (OP)]

@yor_on The OP is asking why the plasma ball reversed the direction of his compass needle, first and foremost.

[yor_on]

Ahh, was thinking of those natural 'plasma balls/ball lightning' that sometimes get reported, not Teslas 'plasma balls' you can have at home.

=
Should I understand it as if this plasma ball reversed his compass permanently too?

[chris (OP)]

Should I understand it as if this plasma ball reversed his compass permanently too?

That's what it sounds like... It would appear that the compass has been remagnetised...

[Colin2B]

The central electrode in these balls has an HF voltage, typically 3kV at 30kHz. The em field extends beyond the globe and will light up a fluorescent tube held near by. I've never heard of one demagnetising a compass, but anything  conductive near the globe can have a current induced in it which might be strong enough to remagnetise. If the compass were placed on a working globe and then removed slowly I would expect the compass to be demagnetised, but if it were on the globe when it was switched off remagnetisation is more likely.
Interesting.

[yor_on]

Thanks Collin.
Exactly what I thought too :)

But how would I know?
Never had one strong enough possibly?

[Colin2B]

But how would I know?
Never had one strong enough possibly?

Maybe you were just sensible enough not to put anything conductive near it.

I never had one

[PmbPhy]

Roy says:

I placed a magnetic compass on top of my plasma ball. Now the compass needle is reversed. Should this happen? If so, could a plasma discharge from the sun reverse the Earth's magnetic field instantly?

What does everyone think?

First, I can't accept that the comments posted regarding demagnetizing the compass can explain why the compass needle is reversed. In fact since you stated that the needle is reversed tells me that it is in fact still magnetized. A time varying current such as that produced by your plasma ball can indeed change the magnetization of a magnet it takes a special procedure to demagnetize a magnet by such a time varying magnetic field. The field has to be reduced in magnitude over a period of time in a special manner. But your needle wasn't demagnetized.

Has this been the case in every instance that you tried it? Try repeating it many times and each time note the polarity of the compass needle and then post the results. I may be better able to understand what's happening if you do such an experiment and post the results.

[sceptic-eng]

Plasma is formed an electric spark so of course an arc welder will produce a huge magnetic energy field which will vibrate your compass almost to death.  However, once the arc current is extinguished the compass will find magnetic north again.

[chris (OP)]

@sceptic-eng - thanks for pointing that out, but my reading of the question was that he's saying his compass re-magnetised in a new direction, because he says "Now the compass needle is reversed."

How could that happen?

[yor_on]

he turned the magnet up side down

No seriously, I think you can do it with a ordinary Tesla ball at home. Someone need to buy one to prove it, then send it to me so we are sure it's reproducible. Or cash will suffice

Ps: extremely expensive those Swedish Tessla balls btw