Circuit Variables

There are four basic variables used in the analysis of electrical networks. They are summerised in the table below.

Name Symbol Definition Notes
Voltage \[\begin{aligned} v(t) \\ \end{aligned} \]
Current \[\begin{aligned} i(t) \\ \end{aligned} \]
Charge \[\begin{aligned} q(t) \\ \end{aligned} \] \[\begin{aligned} q(t) \triangleq \int_{-\infty}^t i(\tau)\,\mathrm{d}t \\ \end{aligned} \] \[\begin{aligned} i = \frac{dq(t)}{dt} \\ \end{aligned} \]
Flux \[\begin{aligned} \varphi(t) \\ \end{aligned} \] \[\begin{aligned} \varphi(t) \triangleq \int_{-\infty}^t v(\tau)\,\mathrm{d}t \\ \end{aligned} \] \[\begin{aligned} v = \frac{d\varphi(t)}{dt} \\ \end{aligned} \]

Passive Circuit Elements

Name Symbol Description
Capacitor
Smiley face
A passive two terminal network element relating charge and voltage.
Inductor
Smiley face
A passive two terminal network element relating flux and charge.
Resistor
Smiley face
A passive two terminal network element relating current and voltage.

Semiconductor Devices

Name Symbol
Diode
Smiley face
CMOS
Smiley face