Answer:
B1 = μ_o•I1/2πr
Explanation:
According to the right hand rule, we can say that the magnetic field at the second wire due to the current being carried in first wire is given by;
B1 = μ_o•I1/2πr
Where;
r is distance that separates the two wires
μ_o is a constant known as permeability of free space
I1 is current in wire 1
