1.same current iis flowing in three infinitely long wires along positive x,y,z directions. the magnetic field at a point (0,0,a) would be what??
the ans is
i(j^ -i^)/2
a.


i dont understand how it is j^ -i^ .
2.an electreon is moving along positive x axis.a uniform electric field exists towards the negative y axis. what should be the direction of magnetic field of suitable magnitude so that the net force on the electron is zero??
ans: negative z axis.
how??