Question

you have seemingly two identical metal rods . One is a permanent magnet and the other is of magnetizable material . How can you determine which is which by:

a) test them on a refrigerator

b ) only use the two metal rods (thus no aid)

Answer 1

@Michele_Laino

Answer 2

please wait I'm trying...

Answer 3

I'm searching for your answer in my physics textbook

Answer 4

yes!

Answer 5

I think that your answer is the first one. Namely, using a refrigerator, we can make the so called "adiabatic demagnetization" of the sample which is not a permanent magnet. That "adiabatic demagnetization" can be obtained using superconductor magnets, and / or liquid Helium

Answer 6

But I think my professor is looking for how to determine which is which by using both methods..

Answer 7

But with the refrigerator, If you have one metall rod that is a permanent magnet, cant you just test if the magnet repells from one end? And the other rod that is just magnetic material should just fall off?

Answer 8

In general a magnetizable sample will undergo an induced magnetization, when it is located into a magnetic field. Furthermore, true magnet, for example will interact with a magnetic compass, whereas the magnetizable sample doesn't interact with a magnetic compass

Answer 9

I assumed that the magnetizable rod is not magnetized

Answer 10

Yeah I dont know, Its a tricky question I think

Answer 11

2 rods only...put the end of 1 to the middle of the other, and repeat....

fridge - just touch fridge with either....

Answer 12

Why the middle? And the rod that isnt magnetic will not lift the magnetic up? @IrishBoy123 ?

Answer 13

When I saw refrigerator, I thought to the adiabatic demagnetization, using the
magneto-caloric effect. I that way, all magnetic properties of the permanent magnet, will be destoryed!

Answer 14

ah okey! but do you know exactly what Irishboy meant? I understand the part with the refrig. but not the other part really

Answer 15

Sincerely I understand part 2, whereas, for part one I have some comment to do. For example, there is no interaction between a permanent magnet, and a magnetizable metal rod (not magnetized), at in the middle of the permanent magnet. Since the magnet interaction, of a permanent magnet, or an electromagnet, is localized at its poles, namely North pole and South pole

Answer 16

more exactly, if the magnetizable rod, is magnetized, there is no interaction with that magnetizable rod, magnetize and the permanent magnet, at the mid point of the permanent magnet, since the magnet action of the permanent magnet, and of the magnetizable rod magnetized are localized at them corresponding poles respectively

Answer 17

@IrishBoy123 can you explain us more, please?

Answer 18

@Michele_Laino
i like your explanation.

in my own words, the field lines at the centre of a bar magnet are much further apart than at the poles. because the field is much weaker. that is how nature behaves.

so, if you apply a dead (unmagnetised) pole to the centre of a bar magnet you might get a bit of attraction/ interaction. however if you apply a live magnetised pole to the centre of an unmagnetised bar, you will get full-on attraction as you would if you applied it to a fridge or paper clip.

Answer 19

If refrigerator, means adiabatic demagnetization, then we apply the adiabatic demagnetization to a permanent magnet, so, after that process, all its magnetic properties will be disappeared

Answer 20

otherwise, we can follow this procedure:
the permanent magnetic rod, will be sensible to the magnetic field of the Earth, like the magnetic compass.
Whereas the metal magnetizable rod, (which I assume, it is not magnetized), is not sensible to the magnetic field exerted by Earth

Answer 21

so the right option should be the second one

Answer 22

i think you are supposed to do both tests and explain how you would explain which is magnetised and which not, in each case. i am not sure as it is not my question but i do not think you are picking a "best of" here.

Answer 23

we have to suspend both rods, with a string, into the air.
The permanent magnet will rotate due to its interaction with the magnetic field of the Earth.
Whereas the magnetizable rod, not magnetized will not rotate