A hollow, right circular cone of base radius \(R\) and height \(h\), with its tip at the origin is rotating about the \(Z\)-axis with an angular velocity \(\omega\), as shown in the figure. The cone carries a total charge \(Q\) uniformly distributed on its curved surface. The magnitude of magnetic field at a point
\[
(0,0,z),
\qquad z\gg R \text{ and } z\gg h
\]
is
\[
\frac{n\mu_0QR^2\omega}{4\pi z^3}
\]
The value of \(n\) is _______.
