how can i tell the polarity of a magnet without a compass, or a previously marked magnet?

Answer 1

You already know the geographic cardinal directions from the movements / apparent movements of the celestial bodies. The magnetic poles are generally aligned with the geographic poles, although, shifting of magnetic poles, is also a well-known occurrence. Thus, knowing the angle of declination, at the time under consideration, you can freely suspend your magnet (in the Earth's magnetic field) and it will align itself as per location of its two own poles (one pole of the magnet, will point towards the Magnetic North Pole of the Earth, at the time; and the opposite pole of the magnet will point towards the Magnetic South Pole of the Earth, at the same time).

You may be aware that the magnetic polarity of the Earth reverses itself, once every 250,000 years, although the next reversal is now overdue by as much as 750,000 years, and the magnetic poles are presently shifting very rapidly. Observatories and science laboratories, all over the world, are studying the phenomenon with great keenness.

Answer 2

Materials Needed:

The magnet
A bowl full of water
A small, flat piece of styrofoam OR a suitable substitute
An adhesive to secure the magnet to the styrofoam

During the sunrise or sunset, take the magnet and secure it to the styrofoam with the adhesive of your choice. Then, set the "raft" gently in the bowl of water. Make sure it is floating freely, otherwise this will not work. Let the magnet float until it settles. Then, find where the sun is. You will be able to find out which direction north is by the sun, as it rises in the east and sets in the west. The pole of the magnet that faces to the north is the south pole, and the other one is the north pole. The south pole is attracted to the magnetic pole of the Earth in the north, in the usual "opposites attract" way.

Answer 3

Put it on a raft, floating on water. The raft will turn, so that the magnets north, points to north.

Edit:
I see that some people are confused about which magnetic pole is called north.
The people who first used a magnetic compass, called the end that pointed toward north, the magnetic north. We now know that opposites attract, and that the magnetic pole close to the geographic north is actually a magnetic south. To make matters worse, the magnetic south are sometimes refereed to as the magnetic north pole, simply because it is located close to the geographic north pole.

Answer 4

Lay your magnet on something that will float - just enough to easily hold the magnet. Set the magnet and its 'boat' in some still water, like a big pot. Now sit down and watch for a few minutes. You'll see that magnet start to spin slowly. It will settle down and stop all on its own. After it has stopped the 'south' pole of the magnet is pointing North. Remember, opposites attract.

Answer 5

use the earth's magnetic field... the end that lines up with the north "north seeking" pole, is the north (placed in floating dish, or hung on a piece of string). It is because the north pole is really the south!

Like the North Magnetic Pole, the geomagnetic north pole is a south magnetic pole, because it attracts the north pole of a bar magnet

Answer 6

float a saucer, with the magnet on it, in a plastic basin of water in your back yard about midday. In the northern hemisphere, the S pole will face the sun, by literally dragging the saucer round.

You can track the magnetic rings in an unusually shaped magnet using iron filings a sheet of A4 and a bit of ingenuity

Answer 7

Put the magnet on top of a TV, oscilloscope or computer monitor (CRT, not flat screen) with the poles oriented left to right. If the image is shifted downward, the left-hand pole is north; if it's shifted upward, the right-hand pole is north.

Answer 8

None here gave you the correct answer. They all suggest using earth as a compass which is not what you asked. The answer is to use an electromagnet fed with dc current. In such electromagnet you can know the poles according to the direction of the current and from this deduct polarity of your magnet.

Answer 9

No, there is south, east and west. Life is fall of ups and downs and the wind blows where it will, nothing to do with magnets, unless of course one is stuck in a rut.

Answer 10

Use another magnet that you know the polarity of. If it repels or attracts then you know!!

The positive pole attracts the negative repels.