Two long straight parallel wires, carrying (adjustable) currents I1 and I2, are kept at a distance d apart. If the force ‘F’ between the two wires is taken as ‘positive’ when the wires repel each other and ‘negative’ when the wires attract each other, the graph showing the dependence of ‘F’, on the product I1I2, would be :
As we learnt in
Force between two parallel current carrying conductors -
I1 and I2 current carrying two parallel wires
a-seperation between two wires
I1 I2 = Positive
Here the force will be attractive and hence it will be taken as negative.
In the second case I1 I2 = Negative
Here the force will be repulsive and hence it will be taken as positive.