Power is the pace of energy provided or consumed by an electric component concerning time.
Voltage and current are the two basic parameters of an electrical circuit. But, voltage and current alone are not sufficient to describe the behavior of an electrical circuit element. We basically need to know how much electrical power a circuit element can handle. We have all seen that a 60 watt electric lamp gives less light than a 100 watt electric lamp. When we pay an electricity bill for electricity consumption, we are actually paying charges for electric power for a specific period of time. Thus the calculation of electrical power is very important for analyzing an electrical circuit or network.
Suppose, an element supplies or consumes dw joules of energy for a time of dt seconds, then the energy of the element can be expressed as,
Subsequently, from the as the outflow of voltage and current in the situation are immediate, the power is likewise quick. The communicated power is time-changing.
Thus, the force of a circuit component is the result of voltage across the component and current through it.
As we have previously informed that a circuit component can either ingest or convey power. We address the retention of force by putting a positive sign (+) in the statement of force. In like manner, we put a negative sign (- ) when we address the power conveyed by the circuit component.
Passive Sign Convention:
There is a straightforward connection between the course of the current, the extremity of the voltage and the indication of the force of the circuit component. We call this straightforward relationship the detached sign show. At the point when current enters a component through a terminal of positive voltage extremity, we put an or more sign (+) before the result of voltage and current. This implies that the component retains or consumes power from the electrical circuit. Then again, when the ongoing through the component leaves its terminal of positive voltage extremity, we put a negative sign (- ) before the result of voltage and current. This implies that the component gives or gives capacity to the electrical circuit.
Allow us to take a resistor associated across two circuit terminals. In any case, the remainder of the circuit isn’t displayed in that frame of mind here. The extremity of the voltage drop across the resistor and the heading of the ongoing through the resistor are displayed in the figure beneath. The resistor is consuming vi watts of force since current I amperes streams into the resistor however its positive-side voltage drop of v volts, as displayed.
Allow us to take a battery associated across two circuit terminals. In any case, the remainder of the circuit isn’t displayed in that frame of mind here. The extremity of the voltage drop across the battery and the course of current through the battery are displayed in the figure underneath. The battery is conveying vi watts of force as an ongoing I ampere enters the battery at v volts through its positive terminal as displayed.