begin notes on ac

uni/mmme/2051_electromechanical_devices/fundamentals.md

@@ -32,6 +32,10 @@ where $V$ is voltage across a component, $I$ is current through it, and $R$ is r
 - Impedance is used when there are energy storage elements to a component.
 - Resistance, a special case of impedance, can be used when there is no storage element
 
+## Admittance
+
+$$Y \frac1Z$$
+
 # Kirchhoff's Laws
 
 ## Current
@@ -84,3 +88,11 @@ Capacitors try to minimize changes in voltage.
 
 If a capacitor is shorted, the current through the connecting wires will be extremely high, causing
 the wires to heat up.
+
+# Root Mean Square (RMS)
+
+$$x_{\text{RMS}} = \sqrt{\frac{x_1^2 + \dots + x_n^2}{n}}$$
+
+For a sinusoidal wave:
+
+$$x_\text{RMS} = \frac{A}{\sqrt2}$$