> [!def|*] Definitions > - **Charge**: fundamental property of matter - *atoms within a volume of water* > - **Current**: rate of change of charge - *water flowing in a pipe* > - Units: Amperes (Amps) > - $I$ or $i$ used in equations > - **Voltage**: related to potential energy of charges, the force produced by charges flowing - *water pressure* > - Units: Volts ($V$) > - $V$ used in equations > - **Resistance/impedance**: prevention of current flow - *gunk in the pipe* > - Units: Ohms ($\Omega$) > - $R$ used in equations > - **Power**: amount of energy available in a circuit at a given time - *how much water is flowing through a pipe at a given moment* ![[Pasted image 20260128171339.png|750]] - Current $i(t)=\frac{dq}{dt}$ and charge $q=\int _{t_{0}} ^t i(t)~ d{t}$ - Power $p(t)=\frac{dW}{dt}=\frac{d}{dt}(qV)=\frac{dq}{dt}(V)=iv$ or conversely $W=\int _{t_{1}} ^{t_{2}}p(t')~ d{t'}$ is energy stored/dissipated within the period $t_{1}$ to $t_{2}$ - Power is *consumed* if [positive] current enters the positive side of voltage source & delivered if [positive] current leaves the positive side of the voltage source