TPRH SW Physics Mistake? Antiparallel Wires?

[onedirection]

Suppose that Wires a and b carry a current of equal magnitdue in opposite directions. If B is the magnitude of the B field created by Wire a at point Q (which lies wihtin the plane defined by the wires and is equidistant from each wire), what ist he magnitdue of the net magnetic fields at point Q due to both wires?

A. 0
B. B/2
C. B
D. 2B

Well the wires are antiparallel

So shouldn't the B field at a point equidistant between the wires simply be 0

The answer key however says 2B which I didn't get and the solutions say that the B field of both wires point downwards when in fact the wires are flowing current in opposite directions

So is the answer A or is it D like the books says?



Associated picture

I'm now lost the next question says that the B field at point P caused by wire ib is pointing upwards

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[monkeyvokes]

the B field wire ib is going to spin circularly (use the right hand rule). The B is traveling up around point P, around the wire, back down around point Q, around the wire, up around P, etc..
Since wire ia's current is traveling the opposite direction, using the right hand rule, the B created also is traveling down through point Q. So, the field at point Q with antiparallel wires should be 2B.

 

[onedirection]

True good call

Appreciate it