Open the door of power and electricity "Circuit" (2): Power Calculation and Judgment

Speaking of power??Oh!!Well, yes, power, as the name suggests, the rate of change of power, the formula is naturally , where the voltage u and current i are instantaneous values, the power calculation friends are already familiar with it, needless to say.

So how do we judge whether a component is absorbing power or emitting power?And what does this have to do with the reference direction?

Good question!!Here I will tell you Shi Qun's simple judgment method. I personally think this method is very nice.

    Power calculation and judgment are divided into two steps:

          1. Suck positive and send negative (the pinyin fa issued is similar to the negative pinyin fu of positive and negative, so mark it as negative when it is issued, and mark it as positive when it absorbs, that’s how I remember it, hehe)

Okay, the two parts are completed as shown below

It should be noted that the substituted voltage and current values ​​are algebraic values. For example, if a component is finally calculated to absorb -24W power, it is equivalent to saying that it emits 24W of power.(The resistive element always absorbs power!!! Others are not necessarily)

Any component can easily judge and calculate the power according to these two parts.See you next time, haha.