Final answer:
Electric power P in a circuit is calculated using the equations P = IV, P = I²R, or P = V²/R, depending on whether current, voltage, and resistance values are known. These equations are derived from the basic principles of electricity and allow for the calculation of power under different circuit conditions, including the overall power in a circuit.
Step-by-step explanation:
The definition of electric power can be derived using three basic equations, which relate power to current, voltage, and resistance. Given the values of current (I), voltage (V), and resistance (R), we can use one of the following equations to calculate electric power (P):
- P = IV, which is the most direct representation of power as the product of current and voltage.
- P = I²R, which is useful when current and resistance are known, and indicates that power is proportional to the square of the current times the resistance.
- P = V²/R, which is handy when voltage and resistance are known, demonstrating that power is proportional to the square of the voltage divided by the resistance.
For instance, when each resistor receives full voltage in a circuit, the power dissipated by each can be calculated using P = V²/R. Similarly, the total power in a circuit can be calculated with P = IV, as seen when multiplying the total current by the total voltage.