What are the characteristics of an ideal voltage source?

An ideal voltage source is defined by its ability to maintain a constant voltage level regardless of the current flowing through it or the resistance of the load connected to it. This means that regardless of how much power is drawn from the source, it can supply the same voltage without any variation. This characteristic is critical for many electrical and electronic applications where a stable voltage is necessary for proper operation.

In contrast, other options do not describe the qualities of an ideal voltage source accurately. For instance, a source that provides variable voltage based on resistance would not be ideal, as it would not offer the stability that is essential for consistent performance. Similarly, the characterization of generating AC voltage only limits the flexibility of a voltage source, as ideal sources can be both AC and DC depending on the application. Lastly, a source that provides zero output when under load would render it ineffective, as it would not be able to supply any power to the connected devices when they require it.

Thus, maintaining a constant voltage regardless of load is the hallmark of an ideal voltage source, making option B the correct choice.