Induced EMF in a Toroidal Solenoid

The current in a toroidal solenoid with 800 turns, a mean radius of 15 cm, and a cross-sectional radius of 2.0 cm is given by the equation $I(t) = (3.0 \, \text{A})(1-e^{-t/\tau})$, where $\tau = 0.10\,\text{s}$. What is the magnitude of the induced emf in the solenoid at time $t = 0.10\,\text{s}$?