What is the function of the brown wire in a cable or plug?

The brown wire in a cable or plug has a specific function, which is to carry the live current to the electrical device it is connected to. This means it delivers the voltage that powers the device. It is essential for the operation of most appliances, providing them with the necessary electrical energy.

The other options do not accurately describe the role of the brown wire. For example, the wire that connects the device to earth is typically the green and yellow wire, which serves as a safety feature to protect users from electric shock. Carrying current away from the component is the role of the neutral wire, which is usually blue. Filtering current is not a function of any of these wires—that's typically performed by devices like transformers or capacitors, not the electrical wiring itself. Thus, the correct identification as carrying the live current clarifies the overall importance of the brown wire in electrical systems.