Question

Two long straight conductors are held parallel to each other at a distance $0.3m$. If the conductors carry currents $2A$ and $8A$ in opposite directions, then what is the distance of the neutral point from the conductor carrying smaller current ?

• A. $0.06m$
• B. $0.24m$
• C. $0.18m$
• D. $0.1m$

Answer 1

The correct option is D $0.1m$

The neutral point from the smaller one be $x$,

$B=\frac{\mu I}{2\pi \times d}$

$B=\frac{\mu \times 2}{2\pi \times x}$

$B=\frac{\mu \times 8}{2\pi \times (0.3-x)}$

equating this eq.

$\frac{\mu \times 2}{2\pi \times x}=\frac{\mu \times 8}{2\pi \times (0.3-x)}$

$2(0.3-x)=8x$

$x=0.1m$