Why some bodies are magnetized?

[abrowaqas]

Why only the magnetic bodies can be strongly magnetized while other bodies like wood, copper, glass e.t.c are hardly affected?

 

[Gerenuk]

(Almost?) All materials are more or less diamagnetic. Diamagnetism originates in changes in the electron orbit, but this effect is quite weak.

Only some materials are ferromagnetic.
https://www.physicsforums.com/showthread.php?t=395265
This effect is different and rather due to rearrangements of the electron spin direction. Ferromagnetism is usually much stronger.

Then there are also paramagnetic materials. There the spins align themselve slightly, but tend to randomize.

Maybe it's best for you to read up about these three type of magnetism :) I might have mixed up some details, but the general idea is OK :)

 

[streeters]

****ing magnets, how do they work?

WELL, most metals are paramagnetic, meaning that their magnetic electrons only align and are magnetic when they are in a magnetic field, and are random when they are not.

Fe, Co and Ni are FERROMAGNETIC, meaning their magnetic electrons keep their alignment when they are out of a magnetic field. Why? They have unbalanced 3d orbitals.

Cu is ANTIFERROMAGNETIC, meaning that they have no magnetic charge even in a magnetic field. Why? The magnetic electrons alternate in opposite directions, so they have no net magnetism

There is also FERRIMAGNETIC materials, such as Fe(x)O(y). This is because there are different types of Iron Oxides (e.g. FeO and Fe2O3) which only partially cancel out the net magnetic moment. So, they have a weaker magnetism.

I'm working from memory here, so research it properly yourself, but I think this won't lead you to far astray.

To understand hard and soft magnetism, look into magnetic domains. well worth it.

EDIT:
oh, wood isn't crystalline, so can't align and can't be magnetic (DIAMAGNETIC)