Question

Assume that in (Figure 1) I = 11 A and d = 60 cm .

What is the magnitude of the force on the first wire?

2.0 cm 2.0 cm I

Answer 1

wires carrying current in same direction attaract each other and wires carrying current in opposite direction repel each other.

2.0 cm 2.0 cmI

r₂ = distance between wire 1 and 2 = 2 cm = 0.02 m

r₃ = distance between wire 1 and 3 = 2 + 2 cm = 0.04 m

F₂ = force on wire 1 by wire 2 = ($\mu$/4$\pi$) (2i²d/r₂) = (10^-7) (2 (11)²(0.60)/0.02) = 7.26 x 10^-4 N

F₃ = force on wire 1 by wire 3 = ($\mu$/4$\pi$) (2i²d/r₃) = (10^-7) (2 (11)²(0.60)/0.04) = 3.63 x 10^-4 N

Net force on wire 1 is given as

F_net = F₂ - F₃ = (7.26 x 10^-4 ) - (3.63 x 10^-4 ) = 3.63 x 10^-4 N