A galvanometer coil has 500 turns and each turn has an average area of $3\times {10}^{-4}{\mathrm{m}}^2$. If a torque of $1.5 \mathrm{Nm}$ is required to keep this coil parallel to a magnetic field when a current of $0.5\mathrm{A}$ is flowing through it, the strength of the field (in $\mathrm{T}$) is _________ .