Polarity of magnetic field in a conducting wire

[acrossingtwo]

When current flows through a copper wire, for example, a magnetic field is produced. What is the polarity of that field? I've seen an example with special relativity and how a positive charge would be deflected. Does that mean the field is negative to a stationary object? Every video I watch says that a wire with current deflects a magnetic object. So then why does an electromagnet attract magnetic objects?

Thank you

 

[davenn]

welcome to PF

When current flows through a copper wire, for example, a magnetic field is produced. What is the polarity of that field?

no idea what videos you were looking at but a magnetic field around a wire is circular so there is no particular polarity
Googling would have given you lots of images of that eg ...

View attachment 220505

View attachment 220506and a zillion more here /...

https://www.bing.com/images/search?...10444162&selectedindex=9&mode=overlay&first=1

so you see asking for a polarity isn't relevant

Every video I watch says that a wire with current deflects a magnetic object.

show us an example

So then why does an electromagnet attract magnetic objects?

A electromagnet is a different story to a straight wire carrying a current. An electromagnet is a coil of wire that may or nay not be wound around an iron core, and in that case the coil generates a polarised magnetic field in/around the coil and core with a N and S pole

have a read of this www site about electromagnets and their polarity

https://www.electronics-tutorials.ws/electromagnetism/electromagnets.html

Dave

 

[Merlin3189]

I'm not a great fan of tricks for solving Physics problems, but since the direction of magnetic and electric fields is purely arbitrary, I do need a mnemonic to help me remember what was decided. Left and right hand rules never worked for me, because I needed another rule to remind me when to use L and when R!

For currents & magnetic fields my Physics teacher gave me a useful mnemonic, which works so long as your language uses N and S for magnetic poles.

This is the face/end view of a coil or solenoid. If you want the field around a wire, just imagine yourself standing on one of the wires of the coil.
Of course, you do need to have a basic understanding of how these fields work in the first place. This is just to give you the sense of the field.