What unit of electricity is equal to the work done when a current of 1 amp is passed through a resistance of 1 ohm for 1 second? Is it a volt, a watt, or a Joule?

When electricity flows through a component like a resistor, it performs work, which is often dissipated as heat. The fundamental unit for measuring work and energy in the International System of Units is the joule. The relationship between power, energy, and time provides the key to understanding why. Electrical power (measured in watts) is calculated as the current squared multiplied by the resistance. Therefore, a current of one amp passing through one ohm of resistance generates one watt of power.

Since energy is simply power multiplied by the time it is used, applying one watt of power for one second results in one joule of energy being transferred. This makes the joule the correct unit for the total work done in this scenario. It's helpful to distinguish this from the other units. A watt measures the rate of energy transfer (joules per second), not the total amount of energy itself. A volt, on the other hand, is the unit of electric potential or "pressure" that drives the current through the circuit.

The unit is named in honor of the English physicist James Prescott Joule. His groundbreaking experiments in the 1840s demonstrated the equivalence of mechanical work and heat, which was a critical step in developing the theory of conservation of energy. Naming the unit of energy after him pays tribute to his foundational contributions to the field of thermodynamics.