IDC = Average currentf0 = mains freqeucnyC = capacitorCalculation:Given f0 = 50 Hz, C = 680 μf, Vdc = 30 V, and RL = 220 Ω, we get:\({I_{dc}} = \frac{{{v_{dc}}}}{{{R_L}}} = \frac{{30}}{{220}}\)Idc = 0.136\({V_r} = \frac{{{I_{dc}}}}{{{f_{oc}}}} = \frac{{.136}}{{50 \times 680 \times {{10}^{ - 6}}}}\)\({V_r} = 4.01\;V\)