Final answer:
The ratio of working power to the total power supplied in a circuit is called the power factor, which reflects the efficiency of power conversion in electrical systems. A power factor of 1 means all supplied power is working power, while a lower value indicates losses due to voltage and current being out of phase in the circuit.
Step-by-step explanation:
The ratio of working power in a circuit to the total power supplied to the circuit is known as the power factor. This is a critical concept in electrical engineering, as it indicates the efficiency with which electrical power is converted into useful work in a circuit. The power factor is influenced by how in-phase the voltage and current are in the circuit; if they are out of phase, the power factor is reduced.
For purely resistive circuits, where the phase angle between current and voltage is zero (p = 0), the power factor is 1, meaning all the power supplied is used as working power. The average power dissipated in such cases can be given by the expression P = I2R, where I is the current and R is the resistance. Using Ohm's law (V=IR), we can also express the power as P = V2/R, indicating a quadratic relationship between voltage and power.
In real-world applications such as transformers, the power factor becomes critical for efficient operation. As per the transformer equation, the voltage and turns ratio must be carefully managed to ensure the intended operation. Overall, the power factor is a measure of how much power is actually doing useful work in an electric circuit as opposed to being 'lost' in the system.