Question

Two long and parallel straight wires A and B carrying currents of 8.0 A and 5.0 A in the same direction are separated by a distance of 4.0 cm. Estimate the force on a 10 cm section of wire A.

Answer 1

Given, two long and parallel straight wires A and B carrying currents of $I_1$ = 8A and $I_2$ = 5A in the same direction are seperated by the distance of $r=4cm$.

we have to find force on l = 10cm wire A.

we know, force of attraction per unit length on two parallel wires carrying currents in same direction is given by,

$\frac{F}{l}=\frac{\mu_0}{4\pi}\frac{2I_1I_2}{r}$

where, $\mu_0$ is permeability of the space (vaccum) i.e., 4π × 10^-7 TmA-¹

so, F/l = (4π × 10^-7)/(4π) × (2 × 8 × 5)/(4 × 10^-2) = 20 × 10^-5 N/m

attractive force on 10cm section of wire A, F = 20 × 10^-5 N/m × 10 × 10^-2 m

= 2 × 10^-5 N