In the circuit shown, V_s is a 10 V square wave of period, T = 4 ms with R = 500 Ω and C = 10 μF. The capacitor is initially uncharged at t = 0, and the diode is assumed to be ideal. The voltage across the capacitor (V_c) at 3 ms is equal to ________ volts (rounded off to one decimal place).