A long, straight wire P carries a current into the page, as shown in the figure below.
A second long, straight wire Q, carrying a current of 
out of the page, is placed parallel to wire P, as shown in the figure below.
The flux density of the magnetic field at wire Q due to the current in wire P is 
.
Calculate the magnetic force per unit length exerted on wire Q by wire P.
State the direction of the force exerted on wire Q by wire P.
The flux density of the magnetic field at wire P due to the current in wire Q is 
. Determine the magnitude of the current in wire P. Explain your reasoning.
.
.
