**RC Time Constant**

Charging and discharging of a 10µF capacitor with variable time constant.

**What it shows:**

The growth and decay of current in an RC circuit with a time constant chosen so that the charge and discharge is visible in real time.

**How it works:**

By choosing the values of resistance and capacitance, a time constant can be selected with a value in seconds. The time constant τ is given by

τ = RC

To obtain useful values, we chose three resistors 100K, 200K and 400K in series with a 10µF capacitor, giving time constants of...