+
+### Faraday's law of induction
+
+$$\epsilon = -N{{\Delta \Phi_B}\over{\Delta t}}$$
+
+where
+$\epsilon$ is induced EMF (voltage)
+$N$ is the number of turns in the primary coil
+$\Phi_B$ is the magnetic flux (Wb or V / s)
+$\Delta t$ is the change in time for one cycle (can be derived from period or frequency)
+
+### Flux through coils
+$$\Phi_B = B_{\perp}A$$
+
+where
+$B_\perp$ is the field strength (Tesla)
+$A$ is the area of the field perpendicular to field lines
+
+if $B {\not \perp} A, \Phi_B \rightarrow 0$
+if $B \parallel A, \Phi_B = 0$
+
+- flux-time graphs ($t$ on $x$-axis): $\operatorname{gradient} \times n = \operatorname{emf}$
+
+
+**EMF is proportionate to change in flux**
+
+**Induced EMF opposes (counters) change in flux**
+
+### Transformer equation
+
+$${V_p \over V_s}={N_p \over N_s}$$
+$${I_p \over I_s}={N_s \over N_p}$$
+
+- core strengthens and "focuses" ac flux $\Phi$ through secondary coil
+
+
+### Root mean square
+
+$$V_{\operatorname{rms}} = {V_{\operatorname{p\rightarrow p}} \over \sqrt{2}}$$
+
+## Power transmission
+- 240 V / 50 Hz in Australia
+- higher voltages have lower $V_{\operatorname{loss}}$
+- ac is used because its voltage is easily changed with xfmrs
+
+### Safety
+- $\ge 30 \operatorname{mA}$ through heart is dangerous
+
+### Transmission $P_{\operatorname{loss}}$
+
+$$P_{\operatorname{loss}} = \Delta V I = I^2 R = {{\Delta V^2} \over R}$$
+
+where
+$R$ is the total resistance (derived from resistance per distance)
+
+To reduce power loss, use lower resistance (thicker) wires or increase voltage / reduce current with transformers
+
+
+