A circuit consists of a variable potential source, a \(200\text{ }\Omega\) resistor, and an initially uncharged \(5.0\text{ }\mu\text{F}\) capacitor connected in series. The variable source is adjusted so that the current \(I\) through the circuit varies with time \(t\) as shown in the graph. What is the potential difference across the variable potential source at time \(t = 6.0\text{ ms}\)?