How is voltage measured in relation to energy?

Voltage is defined as the amount of energy transferred per unit charge. It represents the potential difference between two points in an electrical circuit and indicates how much work can be done by the electric charge when it moves through an electric field. In practical terms, this means that if you have a higher voltage, a greater amount of energy is available to be converted into other forms of energy (like light, heat, or motion) when the charge moves through the circuit.

The correct answer highlights this fundamental relationship, where voltage is quantified as energy divided by the amount of charge (measured in coulombs). This principle is crucial for understanding how electrical energy is harnessed and utilized in various applications.

In contrast, the other options do not accurately capture the definition of voltage in this context. For instance, energy per unit resistance, unit power, or unit capacitance only relate to different aspects of electrical properties and do not define voltage in terms of energy and charge. Thus, option B clearly articulates the standard definition of voltage in the study of electricity.