electromagnetism

I suppose conductor Q is above conductor P, and both are carrying a current.
The direction of magnetic force is pointing into the paper.

The current in conductor P produces a magnetic field on conductor Q. The field lines are from left to right, as determined using the Right Hand Grip Rule.

Resolve the field lines into two perpendicular components, one is perpendicular to conductor Q, named as B1, say, and the other is along the current direction in conductor Q, named as B2, say.

Field B2 provides no magnetic force on conductor Q. The direction of magnetic force produced by field B1 is determined by using Fleming's Left Hand Rule (the Motor Rule), and which is found to be pointing into the paper.