Question

Magnetic Field/ Force problem help please

Answer 1

I thought I could use Ampere Law? No?
I divided 1.38 x 10^-5 Tm by 4 pi x 10^-7 T/m/A = 11 A

Answer 2

Do I have to take into account the current outside ?

Answer 3

I3 - 12 A = 11 A then?

Answer 4

So, the other currents don't matter?

Answer 5

They don't

Answer 6

Yeah, that's the confusing part since I don't know the direction of I3? That's how you determine if you add or subtract right?

Answer 7

Sorry, I forgot the problem. See, the circulation of the magnetic field is clockwise, so the sum of currents must be inwards.

Answer 8

therefore the net current must be 11 A inwards... which leaves us with the only possibility that I1 is inwards (if it is outwards, both currents will be outwards and so we cannot have this possibility)

so I1 - 12 A = 11 A it is

Answer 9

Ohh, so I3 = 23 A inwards. since it's a "larger" current, the net current is inward?

Answer 10

yeah exactly!

Answer 11

Awesome! Thanks!