An uncharged parallel-plate capacitor is connected in series with a resistor of resistance \(R\) and an ideal DC voltage source of constant potential difference \(V_0\). At time \(t = 0\text{ ms}\), a switch is closed to begin charging the capacitor. At time \(t = 5\text{ ms}\), after the circuit has reached a steady state, a dielectric slab is rapidly inserted between the plates of the capacitor while it remains connected to the voltage source. The current \(I\) through the resistor as a function of time \(t\) is shown in the graph. Based on the graph, what is the dielectric constant \(\kappa\) of the inserted material?