Question

Consider the three long,straight,parallel wires as shown in figure.Find the force experienced by a 25 cm length of wire C.

• A. $2\times {10}^{-4}N$
• B. $3\times {10}^{-4}N$
• C. $5\times {10}^{-4}N$
• D. $6\times {10}^{-4}N$

Answer 1

Answer: (B)

$3\times {10}^{-4}N$

Repulsion by wire D ...... (towards right)

$F_1=\frac{{\mu }_o}{2\pi }\frac{i_1{i}_{2}l}{r}$

$=\frac{(2\times {10}^{-7})(30\times 10)}{3\times {10}^{-2}}\left(0.25\right)$

$=5\times {10}^{-4}N$

Repulsion by wire G ....... (towards left)

$F_2=\frac{(2\times {10}^{-7})(20\times 10)}{5\times {10}^{-2}}\left(0.25\right)$

$=2\times {10}^{-4}N$

$\therefore F_{net}=F_1-F_2$

$=3\times {10}^{-4}N$ (towards right)