A capacitor discharges through a resistor.

A capacitor discharges through a resistor. The voltage follows $V = V_0 e^{-t/\tau}$, where $\tau$ is the time constant. The voltages at 0, 2, 4, 6, 8 and 10 ms are 9.0, 6.1, 4.1, 2.7, 1.8 and 1.2 V. Fit the law with curve_fit, with the parameters $V_0$ and $\tau$ (write the model with $\tau$ directly, and not $1/\tau$). Find $\tau$ with its uncertainty, and the time when the voltage falls to 1 V.