Demagnetizing fields

Demagnetizing fields

The Hc column in the data table above indicates the strength of a magnetic field which can demagnetize a magnet. The magnet would have to be subjected to it in an opposing or repelling manner.

Experiment

1. Obtain samples of ceramic magnets, alnico magnets and a NdFeB magnet. Mark the North pole on each magnet (use a compass to determine which is the N end of each magnet. Remember, the South end of the compass will point to the North pole of your magnet).

2. Measure the strength of the flux using the same method suggested above for measuring temperature affects. Write down your observations. Then check the polarity of the magnet using your compass. Write down your observations.

3. Take the NdFeB magnet and place it against the ceramic magnet, North pole against North pole. Leave it there for a day. Tape or rubber-band the magnets together to keep them in that position. Do the same thing with the alnico magnet and the NdFeB magnet the next day.

4. Measure the strength of the flux for each magnet again and note the difference. Also check its polarity. Write down your observations.

5. Now, take the NdFeB magnet and place its South pole against the marked North pole of the ceramic magnet. Leave it there for a day. Do the same thing with the alnico magnet and the NdFeB magnet the next day.

6. Again, measure the strength of the flux for each magnet and note the difference. Also check its polarity. Write down your observations.

7. You should see that the flux measurement for the NdFeB magnet does not change. However, the ceramic and alnico will change greatly. The poles of the alnico magnet may even become reversed in step 3.

Tags: neodymium magnets Demagnetizing fields Smco magnets