Two long parallel straight wires separated by 5 cm carry currents of 2.5 A and 4.0 A, respectively. What is the force per unit length on one of the wires due to the other?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 4 × 10−5 N/m
Two long parallel current-carrying wires exert a force on each other; the force per unit length is
\( \displaystyle \frac{F}{l} = \frac{\mu_0 I_1 I_2}{2\pi d} \)
\( \frac{\mu_0}{2\pi} = 2\times10^{-7}\,\mathrm{T\,m\,A^{-1}} \)
\( \displaystyle \frac{F}{l} = \frac{2\times10^{-7} \times 2.5 \times 4.0}{5\times10^{-2}} \)
\( \displaystyle \frac{F}{l} = 4\times10^{-5}\,\mathrm{N\,m^{-1}} \)