Two long straight parallel wires P and Q are situated a distance 
apart, as illustrated in the figure below.
The current in wire P is 
. The current in wire Q is 
. The magnetic flux density 
at a distance 
from a long straight wire carrying current 
is given by the expression
where 
is the permeability of free space. Calculate:
the magnetic flux density at wire Q due to the current in wire P
the force per unit length, in 
, acting on wire Q due to the current in wire P.
.
