The unit of current, the ampere, is defined in terms of the force between currents. Two 1.0-meter-long sections of very long wires a distance 2.5 m apart each carry a current of 1.0 A. You may want to review (Pages 784 - 787) . What is the force between them?

1.6 x N

Explanation:

If the force between two actual wires has this value, the current is defined to be exactly 1 A.

The force between two parallel wires carrying current can be defined as,

F=  μ L/ 2πd

where,

current = 1Amp

current = 2amp

Length 'L'= 1m

distance 'd'= 2.5m

permeability of free space 'μ'= 4πx N/m

Putting the above values in the equation,

F=( 4πx x 1 x 2 x 1 )/ 2πx2.5

F= 1.6 x N