Answer: 2.66×10^-5 N/m
Explanation: If two current carrying conductor are separated by a distance (r) from each other, they exert a force per unit length on each other (either attractive or repulsive) which generates a magnetic field, the force per unit length is defined by the formulae below.
F/L = (u×I1 ×I2) /(2πr)
Where F/L = force per unit length
u = permeability of free space = 1.256×10^-6 mkgs^-2A^-2
I1 = current on first conductor = 5A
I2 = current on second conductor 8A
r = distance between conductors = 0.30m
F/L = (1.256×10^-6 × 5× 8)/ 2 × 3.142 × 0.30
F/L = 0.00005024/1.8849
F/L = 0.0000266 = 2.66×10^-5 N/m