When the load is open, the capacitor in the capacitor filter circuit of the single-phase half-wave rectifier circuit will be forced to discharge, because no current flows through the load at this time, and the diode in the rectifier circuit will not conduct, so no current enters the capacitor, and the capacitor will gradually discharge through its internal resistance, resulting in the output voltage gradually decreasing until it is close to zero. Therefore, when the load is open, the output voltage of the single-phase half-wave rectifier capacitor filter circuit will be reduced to near zero.