Question

Two long parallel wires are at a distance of $1$ metre. Both of them carry one ampere of current. The force of attraction per unit length between the two wires is

• A. $5 \times {10} ^{-8} N/m$
• B. $2 \times {10} ^{-8} N/m$
• C. $2 \times {10} ^{-7} N/m$
• D. $ {10} ^{-7} N/m$

Answer 1

Answer: (C)

$F= \frac{{\mu}_0 }{4 \pi} \frac{2 I_1 I_2}{r} = \frac{ {10}^{ -7} \times 2(1) \times (1)}{1}$
$ = 2 \times {10}^{-7} \,N/m $