Question

Find the net force on the square frame ABCD.

• A. $0.8\times {10}^{-5}$, repulsion
• B. $0.8\times {10}^{-5}$, attraction
• C. $0.4\times {10}^{-5}$, attraction
• D. $0.4\times {10}^{-5}$, repulsion

Answer 1

The correct option is B $0.8\times {10}^{-5}$, attraction


Force on the loop ABCD:
$F_{A}B=2\times {10}^{-7}\times \frac{30}{5\times {10}^{-2}}\times 10\times {10}^{-2}N$
$=1.2\times {10}^{-5}N$
$F_{CD}=2\times {10}^{-7}\times \frac{30}{15\times {10}^{-2}}\times 10\times {10}^{-2}$
$=0.4\times {10}^{-5}$
$F_{net}=1.2\times {10}^{-5}-0.4\times {10}^{-5}$
$=0.8\times {10}^{-5}N$