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 \( (0, 0, z) \), where \( z \gg R \) and \( z \gg h \), is \( \dfrac{n \mu_0}{4\pi} \dfrac{Q R^2 \omega}{z^3} \). The value of \( n \) is:
