Short Answer 
A half-wave rectifier only allows one half of an AC cycle to pass, converting it to a pulsating DC output while maintaining the same frequency. For example, a 50 Hz AC input results in a 50 Hz ripple output, as the rectifier produces one pulse for each cycle of AC, keeping the fundamental frequency unchanged.
Step 1: Understand the Half-Wave Rectifier
A half-wave rectifier is an electrical device that only allows one half of an alternating current (AC) cycle to pass through. It effectively converts AC voltage into direct current (DC) by blocking the negative half of the input waveform. This results in a pulsating DC output, where each pulse corresponds to one cycle of the original AC frequency. The process is essential for applications requiring DC voltage.
Step 2: Frequency of Input and Output
When a 50 Hz alternating voltage is applied to a half-wave rectifier, the ripple frequency of the output remains the same, at 50 Hz. This is because the rectifier allows only one half of each AC cycle to be utilized, creating a ripple that appears at the same frequency. Essentially, for every cycle of input, there is one corresponding pulse in the output.
Step 3: Ripple Frequency Explained
The frequency of the output ripple is directly tied to the input AC frequency; hence, the 50 Hz input leads to a 50 Hz ripple output. This output maintains the same fundamental frequency, even though its waveform is altered. Key points to remember include:
- The ripple frequency is determined by the input frequency.
- A half-wave rectifier produces one pulse for each AC cycle.
- The fundamental frequency of the input remains unchanged in the output.