A conducting ring of circular cross-section with inner and outer...

A conducting ring of circular cross-section with inner and outer radii $a$ and $b$ is made out of a material of resistivity $ρ$. The thickness of the ring is $h$. It is placed coaxially in a vertical cylindrical region of a magnetic field $B = krt$, where $k$ is a positive constant, $r$ is the distance from the axis and $t$ is the time. If the current through the ring is $I = \left(\dfrac{kh}{\alpha p}\right)\left[{b}^{3} - {a}^{3}\right]$, then what is the value of $\alpha$?