Question

The force per unit length between two long straight conductors carrying currents 3 A each in the same direction and separated by a distance of 2.0 cm is :

• A. $9\times {10}^{-7}N/m$
• B. $9\times {10}^{-6}N/m$
• C. $9\times {10}^{-5}N/m$
• D. $9\times {10}^{-4}N/m$

Answer 1

The correct option is C $9\times {10}^{-5}N/m$

The force per unit length between two long straight current carrying conductors is given by $F=\frac{{\mu }_0{I}_1{I}_2}{2\pi d}$

Here, current in the conductors $I_1=I_2=3A,$

Distance between the two conductors, $d=2cm=0.02m$,

So, $F=\frac{4\pi \times {10}^{-7}\times 3\times 3}{2\pi \times 0.02}=9\times {10}^{-5}N/m$