# How to find the direction of the magnetic field for an infinite conducting wire?

We've got two long straight wires carrying current of 5A and placed along x and y axis respectively current flows in direction of positive axes we have to find magnetic field at a) (1 m,1 m) b) (-1 m,1 m) c) (-1 m,-1 m) d) (1 m,-1 m) now using ampere's law $$\oint_{}^{}B.dl=\mu_oi$$ i found magnetic field for infinite wire be $$B=\frac{\mu_oi}{2\pi r}$$ where r is distance from the wire but for evaluating the magnetic field we need to know direction of it and thus add it like vector but finding direction of magnetic feild at these point is confusing me , how do i find proper direction of magnetic field ?

-
You use the right hand thumb rule to find the direction of the magnetic field due to any current carrying conductor. Here you'll find ways to use the right hand thumb rule: physics.stackexchange.com/questions/45747/… – udiboy1209 Aug 10 '13 at 14:13
You should also note that $\vec B$ is fundamentally defined as $\mu_0 /4\pi i (\vec {dl}\times\vec r)$, so $(\vec {dl}\times\vec r)$ will give the direction of the magnetic field. – udiboy1209 Aug 10 '13 at 14:17