Which of these quantities is NOT a unit of measurement in electrical theory?

The quantity that is not a standard unit of measurement in electrical theory is Watt per hour. In electrical systems, power is typically measured in watts, which quantifies the rate of energy transfer. The term "watt" itself describes how much energy is used in a circuit over a period of time, specifically one watt equals one joule per second.

While "watt-hours" is a common measure of energy (indicating how much energy is consumed or produced over a span of time), "watt per hour" is not a standard unit used in electrical theory. It implies a rate of change of power over time, which is not a typical context for electrical measurement.

On the other hand, volt, ohm, and coulomb are all established units within electrical theory: volts measure electric potential, ohms quantify electrical resistance, and coulombs represent electric charge. Each of these plays a crucial role in understanding and quantifying electrical phenomena, making them valid units in the field.