Red Seal Instrumentation and Control Technician Practice Exam

Which device is used for converting alternating current (AC) to direct current (DC)?

1. Transformer

2. Rectifier

3. Inverter

4. Inductor

The correct answer is: Rectifier

The device used for converting alternating current (AC) to direct current (DC) is a rectifier. Rectifiers operate by allowing current to flow only in one direction, effectively blocking the reverse flow that is characteristic of AC. This process is typically achieved through the use of diodes, which conduct current when forward-biased and block it when reverse-biased. As a result, the output of a rectifier is pulsating DC, which can be further smoothed to provide a more steady direct current through filters. Transformers, on the other hand, are designed to change the voltage level of AC power but do not convert AC to DC. An inverter performs the opposite function of a rectifier, converting DC back into AC. Inductors, while they are components that can store energy in a magnetic field, do not serve the purpose of converting AC to DC. Understanding the specific functions of these devices is crucial for anyone working in instrumentation and control, as it directly relates to how electrical power is processed and utilized in various applications.