Two long parallel wires, each carrying a current of 2 a, lie a distance 25 cm from each other. if the distance between the wires is tripled, (a) by what multiplicative factor is the force per unit length changed?

the force will become 1/3 times the initial force

Explanation:

As we know that force between two current carrying wires is given by the formula

here we know that

= currents flowing in two wires

L = length of the wire on which force is to be calculated

d = distance between two wires

now let say the distance between the wires is "d"

so the force between the wires will F1

now the distance is increased by factor of 3

so the force between the wires is given as

so here we can say that the new force between two wires is decreased by factor of 3

so the force will become 1/3 times the initial force

where are the vectors ?