ece140: day 1 update

docs/1b/ece140.md

@@ -1,3 +1,25 @@
 # ECE 140: Linear Circuits
 
 ## Voltage, current, and resistance
+
+Please see [SL Physics 1#Electric potential](/g11/sph3u7#electric-potential) for more information on voltage.
+
+Please see [SL Physics 1#5.2 - Heating effect of electric currents](/g11/sph3u7/#52-heating-effect-of-electric-currents) for more information on current.
+
+Please see [SL Physics 1#Resistance](/g11/sph3u7/#resistance) for more information on resistance.
+
+**Electric charge** $Q$ quantises the charge of electrons and positive ions, and is expressed in coulombs (**C**).
+
+Objects with charge generate electric fields, thus granting potential energy that is released upon proximity to another charge.
+
+!!! warning
+    Voltage and current are capitalised in **direct current only** ($V$, $I$). In general use, their lowercase forms should be used instead ($v, $i$).
+
+**Voltage** is related to the change in energy ($dw$) over the change in charge ($dq$), or alternatively through Ohm's law:
+
+$$i=\frac{dw}{dq}=\frac{i}{R}$$
+
+**Current** represents the rate of flow of charge in amps (**A**). Conventional current moves opposite electron flow because old scientists couldn't figure it out properly.
+
+$$i=\frac{dq}{dt}\approx \frac{\Delta q}{\Delta t}$$
+

docs/1b/math119.md

@@ -21,5 +21,5 @@ $$f: \mathbb R^n \to \mathbb R$$
     - A **level curve** is a slice of a three-dimensional graph by setting to a general variable $f(x, y)=k$. It is effectively a series of contour plots set in a three-dimensional plane.
     - A **contour plot** is a graph obtained by substituting a constant for $k$ in a level curve.
 
-Please see [level set](https://en.wikipedia.org/wiki/Level_set) and [contour line](https://en.wikipedia.org/wiki/Contour_line) for example images.f
+Please see [level set](https://en.wikipedia.org/wiki/Level_set) and [contour line](https://en.wikipedia.org/wiki/Contour_line) for example images.