What is the definition of a watt?

A watt is defined as a unit of power that quantifies the rate at which energy is used or produced. Specifically, one watt is equivalent to one ampere of electric current flowing under the pressure of one volt. This relationship is based on the formula for electrical power, which is expressed as power (in watts) equals voltage (in volts) multiplied by current (in amperes). Therefore, option B accurately reflects this definition, making it the correct choice.

The other choices are related to energy and electrical concepts but do not define a watt. For instance, measuring the total energy consumed over time relates to watt-hours, and therefore would align more with option A as a description of total energy rather than the rate of power consumption defined in watts. Electrical resistance, as mentioned in option C, pertains to the opposition to the flow of electric current measured in ohms, which is a different concept entirely. Lastly, while solar panels do produce energy, the total energy produced doesn’t define the watt itself; option D is more about the output of a solar panel rather than a unit of measurement for power.