Which of the following statements is true regarding the flow of current in a half-wave rectifier?

In a half-wave rectifier, the correct understanding is that it allows current to flow only during the positive half cycle of an alternating current (AC) waveform. This is due to the function of the diode used in the rectifier, which is designed to conduct electrical current in one direction only.

During the positive half of the AC cycle, the diode becomes forward-biased, allowing current to pass through to the load. In contrast, during the negative half of the cycle, the diode is reverse-biased and blocks the current flow completely. As a result, the output from a half-wave rectifier consists solely of the positive half cycles of the input AC signal, while the negative half cycles are eliminated. This characteristic forms the basis of how half-wave rectification operates, making the specific statement about allowing current flow only during the positive half cycle accurate.

The other options describe behaviors that do not align with the operational principles of a half-wave rectifier. The device cannot allow current during both cycles, nor does it switch between positive and negative cycles, as by design, it only allows a flow during one specific direction and one segment of the waveform.