To convert AC to DC in commercial adapters, a bridge rectifier is utilized, which employs diodes to ensure current flows in one direction by converting the negative troughs of the AC sine wave into positive peaks. This process results in a pulsating DC output, which is then smoothed using a capacitor to reduce fluctuations in the waveform. The mechanical analogy compares this system to check valves that ensure water flows in one direction, with a bucket representing the capacitor that stabilizes the flow. Understanding the role of diodes and capacitors is crucial for grasping how these adapters function. This knowledge is essential for anyone interested in electrical engineering and power conversion technologies.