Q14

An investigation was performed with the aim of measuring the value of the magnetic permeability constant, $\mu_0$.

Two wires, both of length $70.0\ \mathrm{cm}$, were arranged horizontally, with one wire above the other, as shown in the diagram below. The bottom wire is resting on an electronic balance.

When a current of $25.5\ \mathrm{A}$ flows through both wires, the reading on the electronic balance changes by $0.500\ \mathrm{g}$.

What is the value of $\mu_0$ as determined by this investigation?
(A) $3.4\times10^{-7}$
(B) $1.7\times10^{-7}$
(C) $3.4\times10^{-4}$
(D) $1.7\times10^{-4}$