# I Magnetic field created by a wire acts on the wire itself?

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1. Dec 20, 2016

### Cozma Alex

So here is the problem, it asks me to find the total magnetic field on BA, i made a vectorial sum with the magnetic field generated by i1 and by i2 and i got the right result, but why not adding also the magnetic field generated by the wire itself? I mean generated by CD why isn't that correct? There is current i glowing in CD too, so it generates a magnetic field, why doesn't this add too? Basically im asking: does a wire carriyng current generate a magnetic field that can imteract with that wire?

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2. Dec 20, 2016

### BvU

You are correct. The exercise doesn't take these 'internal' forces into account because they don't influence the net force on the complete loop ABCD.

3. Dec 20, 2016

### Cozma Alex

So... if it asks me the total magnetic field on BA and doesn't take under account the field generated by CD the book gave me a wrong result? Thanks

4. Dec 20, 2016

### BvU

I agree. It asks for the total magnetic force on AB and for the total force on CD. The 75.6 $\mu$T in the answer for AB ignores the field produced by BC (88.4 $\mu$T)