Why do north and south poles attract in electromagnets and bar magnets?

[Pulzz]

I've always been taught: North poles attract south poles. Yesterday after studying electromagnetism, I've a question to ask. Here's a diagram:

In circuits like these, this is how the north and south poles of these electromagnets are defined. Now my question is, is the reason that the South pole of the first electromagnet(Its backside) attracted to the front of the electromagnet in the back because the two circuits have current flowing in the same direction? Is this why in general the north pole attracts the south pole? How does this work in a permanent magnet such as a bar magnet?

 

[davenn]

Hi there
Welcome to PF

I've always been taught: North poles attract south poles. Yesterday after studying electromagnetism, I've a question to ask. Here's a diagram:...
In circuits like these, this is how the north and south poles of these electromagnets are defined. Now my question is, is the reason that the South pole of the first electromagnet(Its backside) attracted to the front of the electromagnet in the back because the two circuits have current flowing in the same direction? Is this why in general the north pole attracts the south pole? How does this work in a permanent magnet such as a bar magnet?

in a straight wire carrying current, there are no north and south magnetic poles as the magnetic field is circular ( a loop) around the wirecheers
Dave

 

[Pulzz]

Hi there
Welcome to PF
in a straight wire carrying current, there are no north and south magnetic poles as the magnetic field is circular ( a loop) around the wirecheers
Dave

I'm sorry, but I don't see how this answer is relevant to my question at all. My question is about two closed loops which produce a magnetic field as such:

 

[davenn]

now if you wind the wire into a coil, then you can create magnetic N and S poles ...

 

[davenn]

I'm sorry, but I don't see how this answer is relevant to my question at all. My question is about two closed loops which produce a magnetic field as such:

because you first drawings were showing straight sections of wire, so my answer was completely relevantD

 

[CWatters]

Now my question is, is the reason that the South pole of the first electromagnet(Its backside) attracted to the front of the electromagnet in the back because the two circuits have current flowing in the same direction? Is this why in general the north pole attracts the south pole?

No. It's to do with the energy of the system. Systems tend to prefer lower energy states. This holds for all sorts of systems including those involving gravity and chemistry.

http://physics.stackexchange.com/questions/64146/the-preference-for-low-energy-states