Two long parallel straight wires A and B are 4.0cm apart in air. Wire A carries a current of 10A into the page, while wire B carries 15A out of the page. Point P is exactly midway between the wires. Calculate the magnitude and direction of the net magnetic field at P. Take μ0=4π×10−7TmA−1.
a) 1.25×10−4T, downward
b) 2.5×10−4T, downward
c) 5.0×10−5T, downward
d) 2.5×10−4T, upward