Question

Two infinitely long straight conductors which are held parallel to each other at a distance $0.4m$ carry currents $20A$ and $10A$ in the same direction. The magnetic induction at a point midway between them is

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

Answer 1

The correct option is A ${10}^{-5}T$

$\left|B\right|=\left(\frac{{\mu }_0{i}_1}{2\pi r_1}\right)-\left(\frac{{\mu }_0{i}_2}{2\pi r_2}\right)$
=$\left(\frac{2\times {10}^{-7}\times 20}{0.2}\right)-\left(\frac{2\times {10}^{-7}\times 10}{0.2}\right)$
=$50\times 2\times {10}^{-7}T$=${10}^{-5}T$