What does Line Voltage (Vl) measure?

Line voltage measures the voltage between the terminals of an alternator, motor, or branch circuit feeder wires. This value is essential in electrical engineering and power distribution because it indicates the potential difference that is available for powering electrical devices. It is the voltage that is supplied by the electrical grid or generated by a power source to operate equipment or carry current through the electrical system.

When considering this context, option B accurately reflects the concept of line voltage as it pertains to its practical application in electrical systems. In contrast, the other options refer to different measurements or contexts that do not define line voltage accurately. For instance, the voltage between two points of a resistor represents a voltage drop across that resistor, and the voltage generated from a single battery pertains specifically to a standalone source rather than the interaction in a circuit. Meanwhile, the total voltage in a single-phase system can refer to a broader concept that includes multiple components operating together rather than the defined voltage across a specific point in a system. Thus, option B precisely captures the essence of line voltage.