Final answer:
The symbol that represents power in the context of electricity is P, and the unit of measurement is the watt (W). The expression for electric power is P = V x I, where V is voltage and I is current. Other expressions involve resistance, such as P = V²/R, indicating that power increases with voltage and decreases with resistance.
Step-by-step explanation:
When talking about electricity, power is the rate at which electrical energy is transferred by an electric circuit. The symbol commonly used to represent power is P, and the unit of measurement for electric power is the watt, abbreviated as W. The basic expression for electric power in a circuit is P = V x I, where P stands for power in watts, V represents voltage in volts, and I denotes current in amperes. Additionally, other expressions for power include P = V²/R and P = I² x R, where R is resistance in ohms. Of specific interest is the relationship P = V²/R, which shows that a lower resistance yields greater power from a given voltage source and that the effect of voltage is squared in this relationship. A practical example of this could be seen when a light bulb designed for 120 V is connected to 240 V, causing the bulb to burn out because the power almost quadruples, overwhelming the bulb's design specifications.