What is the function of a transformer in a computer system?

The function of a transformer in a computer system is best described by its role in reducing voltage to provide an appropriate DC supply. In many power supply designs, especially those that convert higher voltages from the wall outlet into usable power for components like the CPU, transformers are key components that step down (or sometimes step up) voltages based on the design requirements.

After electricity passes through the transformer, it is typically rectified and regulated to convert AC voltage into a stable DC voltage, which is needed for the logic circuits and processors within the computer. This process ensures that the voltage supplied to the various components is safe and effective for their operation, allowing the system to perform reliably without risking damage from excessive voltage.

In contrast, while transformers can convert AC voltage to higher levels and can be part of noise filtering in power supplies, their primary role in the context of a computer system is not focused on these aspects. Rather, the emphasis is on voltage regulation to ensure appropriate levels for the internals of the computer, which highlights the importance of option B.