The current passing through a conducting loop in the form of equilateral triangle of side \( 4\sqrt{3}\ \text{cm} \) is \( 2\,\text{A} \). The magnetic field at its centroid is \( a \times 10^{-5}\ \text{T} \). The value of \( a \) is ______.
(Given: \( \mu_{0} = 4\pi \times 10^{-7} \) SI units)
