Help are any of these even correct?

  • Thread starter Thread starter cuppy
  • Start date Start date
  • Tags Tags
    even
AI Thread Summary
The discussion centers on the confusion surrounding why the north pole of a bar magnet points north, with various explanations provided. The consensus is that the north pole of a magnet is attracted to the Earth's magnetic south pole, which is located near the geographic north pole, leading to the misconception that they are the same. It is clarified that a compass needle points toward the magnetic field lines, with the north-seeking end actually being a magnetic south pole. Additionally, the magnetic north pole is not fixed and shifts position over time, which has been highlighted in media reports. Overall, the key takeaway is that the terminology can be misleading, as the magnetic north pole is indeed a south-seeking pole.
cuppy
Messages
8
Reaction score
0
I've done some background research but can't find a definite answer to this question. At first i suspected the answer to be A but everyone seems to have their own thoughts about it:

The reason the north pole of a bar magnet (which is free to rotate) points north is because:

a. the south geographic pole of the Earth is the Earth's magnetic north pole

b. the south geographic pole of the Earth is the Earth's magnetic south pole

c. there is a net accumulation of negative charge at the Earth's south geographic pole

d. there is a net accumulation of positive magnetic charge at the Earth's north geographic pole

e. the north geographic pole of the Earth is the Earth's magnetic north pole

i'm pretty sure c and d can be eliminated but that still doesn't make the question much easier to answer
 
Physics news on Phys.org
They are all wrong.

The geographic and magnetic poles do not coincide.

A magnet aligns itself with the magnetic field lines.

The magnetic field lines stretches from the north pole towards the south pole of a magnet. This means that the noth pole of a magnet will point towards the south pole of another magnet (unlike poles attrack each other). The N point of a compass is therefore actually the south pole of a magnet.
 
Last edited:
I'm not quite sure that explanation is quite correct.

This explanation may work better for you. When the phenomenon was first discovered, it was noticed that one end of a bar magnet would orient itself toward Earth's North Pole. This end of the bar magnet was called the north-seeking pole, or shortened, N. So, your bar magnet has two poles: N and S. The S is really the "south seeking pole."

Now, if you think about magnets merely as having "north and south poles", then for the north pole of a magnet to be attracted to Earth's north pole, then Earth's north pole is actually a magnetic south pole. This really isn't a problem though, because it means "south seeking pole" - which of course, opposite poles of a magnet are attracted to each other, thus regardless of what we call Santa Claus country, it's going to be attracted to penguin-land.

A compass needle points in the direction of the magnetic field. Lines of flux are drawn from North to South. So, it will orient itself pointing to the "S" on a bar magnet. In order for it to do this, the tip of the compass needle (on the side it points to) must be a "N-pole". Thus, a compass points toward "S", and Earth's North pole is a magnetic S-pole.
 
Last edited:
Oh, and for what it's worth, choices b and e are essentially the same. You are correct that it's answer A, although andrevdh is correct in pointing out that the geographic north pole and magnetic north pole are not in the same place.

I should emphasize though, it's called "The Magnetic North Pole" - it IS the North Pole. And, of course, as a north pole, it's going to be south-seeking. Bar magnets are labeled by which pole they're seeking, so if you label the Earth as a bar magnet (and in reality, the source of the magnetic field is NOT bar shaped; that's another discussion though) then you need to label that thing up in the Arctic Ocean a "south-seeking pole" or S. But, again, it IS the Magnetic North Pole.

And, as andrevdh noted, it's not located at the geographic north pole. Plus, it moves around a bit, varying daily, and changing location by about 10 to 50 kilometers each year. The changing location of the magnetic north pole hasn't been missed by the media. They love to sensationalize on such things; there were several such stories a few months ago.

Here is a site that seems to have some quality info, if you need more:
http://gsc.nrcan.gc.ca/geomag/nmp/northpole_e.php
 
Last edited by a moderator:
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top