Question

Two long, straight wires are fixed parallel to one another a distance do apart. The wires carry equal constant currents 1, in the same direction. The attractive magnetic force per unit length between them if f = F/L. What is the force per unit length between the wires if their separation is 2d, and each carries current 210? 10 da lo A. f/4 B. f/2 C. 3f/2 D. 2f

Answer 1

Answer:

The option (B) is correct.

Explanation:

The magnetic force between the two current carrying wires is given by

$F =\frac{\mu o}{4\pi}\times \frac{2 I I'}{r}$

where,  I and I' be the currents in the wires and r is the distance between the two wires.

Here, we observe that the force between the wires is inversely proportional to the distance between them.

So, when the distance is doubled , let the new force is F'.

$\frac{F'}{F}=\frac{r}{r'}\\\\\frac{F'}{F}=\frac{d}{2d}\\\\F'=\frac{F}{2}$

So, option (B) is correct.