Chapter 20 complete

content/chapter01.tex

@@ -77,20 +77,20 @@
 
 		\begin{center}
 			\begin{tikzpicture}
-				\draw [line width=0.5mm, ->] (0,0) -- (2,2) node[anchor=south east, pos=0.5]{\(\vec{\mathbf{v}}\)};
-				\draw [line width=0.25mm, dashed, ->] (0,0) -- (2,0) node[anchor=north, pos=0.5] {\(\vec{\mathbf{v}}_x\)};
-				\draw [line width=0.25mm, dashed, ->] (0,0) -- (0,2) node[anchor=east, pos=0.5] {\(\vec{\mathbf{v}}_y\)};
+				\draw [line width=0.5mm, -latex] (0,0) -- (2,2) node[anchor=south east, pos=0.5]{\(\vec{\mathbf{v}}\)};
+				\draw [line width=0.25mm, dashed, -latex] (0,0) -- (2,0) node[anchor=north, pos=0.5] {\(\vec{\mathbf{v}}_x\)};
+				\draw [line width=0.25mm, dashed, -latex] (0,0) -- (0,2) node[anchor=east, pos=0.5] {\(\vec{\mathbf{v}}_y\)};
 				\draw (0.5,0) arc (0:45:0.5) node[pos=0.5, anchor=west] {\(\theta\)};
 			\end{tikzpicture}
 		\end{center}
 
 		Observer that when you add the two components together, they form the vector itself.
 		\begin{center}
 			\begin{tikzpicture}
-				\draw [line width=0.5mm, ->] (0,0) -- (1,2) node[anchor=south east, pos=0.5] {\(\vec{\mathbf{u}}\)};
-				\draw [line width=0.2mm, dotted, ->] (2,-3) -- (3,-1) node[anchor=north west, pos=0.5] {translated \(\vec{\mathbf{u}}\)};
-				\draw [line width=0.5mm, ->] (0,0) -- (2,-3) node[anchor=north east, pos=0.5] {\(\vec{\mathbf{v}}\)};
-				\draw [line width=0.2mm, dotted, ->] (1,2) -- (3,-1) node[anchor=south west, pos=0.5] {translated \(\vec{\mathbf{v}}\)};
+				\draw [line width=0.5mm, -latex] (0,0) -- (1,2) node[anchor=south east, pos=0.5] {\(\vec{\mathbf{u}}\)};
+				\draw [line width=0.2mm, dotted, -latex] (2,-3) -- (3,-1) node[anchor=north west, pos=0.5] {translated \(\vec{\mathbf{u}}\)};
+				\draw [line width=0.5mm, -latex] (0,0) -- (2,-3) node[anchor=north east, pos=0.5] {\(\vec{\mathbf{v}}\)};
+				\draw [line width=0.2mm, dotted, -latex] (1,2) -- (3,-1) node[anchor=south west, pos=0.5] {translated \(\vec{\mathbf{v}}\)};
 				\draw [line width=0.5mm, ->>] (0,0) -- (1.5,-0.5) node[anchor=north] {\(\vec{\mathbf{u}} + \vec{\mathbf{v}}\)};
 				\draw [line width=0.5mm] (1.5,-0.5) -- (3,-1);
 			\end{tikzpicture}
@@ -138,9 +138,12 @@
 				\draw [dashed] (0,5) -- ++(250:5) node (x) {};
 				\draw [dashed] (0,5) -- ++(290:5) node (y) {};
 				\draw (0,4.25) arc (270:250:0.75) node[pos=0.5, anchor=north] {\(\theta\)};
+				\draw (-3,5) -- (3,5);
+				\fill [pattern=north east lines] (-3,5) rectangle (3,5.1);
 				\filldraw [color=black] (0,0) circle (0.25);
 				\filldraw [color=gray] (x) circle (0.25);
-				\filldraw [color=gray] (y) circle (0.25);;
+				\filldraw [color=gray] (y) circle (0.25);
+				\draw[latex-latex] ({5*sin(-20)},-0.35) -- (0,-0.35) node[pos=0.5, anchor=north] {\(A\)};
 			\end{tikzpicture}
 		\end{center}
 

content/chapter16.tex

@@ -37,6 +37,8 @@
 
 		\pdef{Electric Field}{An electric field is a region of space whereby a charge experiences an electric force.}
 
+		Electric field lines \textbf{cannot cross}.
+
 		\begin{center}
 			\begin{tikzpicture}
 				\foreach \x in {1,...,9}
@@ -84,7 +86,7 @@
 
 		Drawing these in TikZ was too difficult so take these from some online website.
 		\begin{center}
-			\includegraphics[width=\linewidth]{graphics/electrostaticsFieldLines}
+			\includegraphics[width=\linewidth]{graphics/electrostaticsFieldLines}\footnote{physics.stackexchange.com}
 		\end{center}
 
 		\subsection{Charging}

content/chapter19.tex

@@ -53,7 +53,7 @@
 	\pdef{Switches}{Switches are designed to break or complete an electrical circuit. They should be fitted to the live wire of the appliance.}
 	\begin{center}
 		\begin{circuitikz}
-			\draw (0,0) to [fuse, l=fuse] (1.5,0) to [spst] (3,0) to[european resistor, l=load] (3,-2) -- (0,-2);
+			\draw (0,0) to [fuse, l=fuse] (1.5,0) to [spst, l=switch] (3,0) to[european resistor, l=load] (3,-2) -- (0,-2);
 			\draw [o-] (-0.5,0) node[anchor=east] {\SI{240}{\volt}} -- (0,0);
 			\draw [o-] (-0.5,-2) node[anchor=east] {\SI{0}{\volt}} -- (0,-2);
 		\end{circuitikz}

content/chapter20.tex

@@ -0,0 +1,82 @@
+\documentclass[../main.tex]{subfiles}
+
+\begin{document}
+	\section{Magnetism}
+	\begin{preamb}
+		Magnets were discovered by who knows who at who knows when. All I know is we have to study them now thanks to lodestone sailor people.
+	\end{preamb}
+	\subsection{Magnets}
+	\pdef{Magnetic Materials}{Magnetic materials are materials that can be attracted to a magnet.}
+	The four materials you probably remember from primary school are: iron, nickel, cobalt, and steel.
+	\pdef{Non-magnetic Materials}{Non-magnetic materials are materials that cannot be attracted to a magnet.}
+	\pdef{Law of Magnetic Poles}{The law of magnetic poles states that like poles repel and unlike poles attract.}
+	Some properties magnets exhibit are
+	\begin{itemize}
+		\item Magnets have two poles: north and south.
+		\item Magnets point in the north-south direction when suspended.
+		\item Like poles repel, unlike poles attract.
+	\end{itemize}
+	Using the property that magnets can repel, we can do the repulsion test to see if an object is a magnet or just a magnetic material.
+
+	\subsection{Magnetic Induction}
+	\pdef{Magnetic Induction}{Magnetic induction is the process whereby an object made of a magnetic material becomes a magnet when it is near or in contact with a magnet.}
+	That means magnetic materials become magnets when in contact or near a magnet.
+
+	\subsection{Magnetisation and Demagnetisation}
+	\pdef{Theory of Magnetism}{\textit{(This is not in syllabus.)} A magnet is made up of many magnetic domains which are made up of atoms that have a ferromagnetic property.}
+	\subsubsection{Magnetisation}
+	You can make a magnet either by stroking it with another magnet, or using electricity to make an electromagnet.
+	\begin{center}
+		\begin{tikzpicture}
+			\draw (0,0) rectangle (3,0.5);
+			\node[anchor=west] at (0,0.25) {N};
+			\node[anchor=east] at (3,0.25) {S};
+			\draw[rotate=45] (2,0) node[anchor=south west, rotate=45] {N} rectangle (5,0.5) node[anchor=north east, rotate=45]{S};
+			\draw[dashed, -latex] (0.5,0.65) -- (2.5,0.65);
+			\draw[dashed, -latex] (2.5,0.65) arc (270:360:1);
+			\draw[dashed, -latex] (-0.5,1.65) arc (180:270:1);
+		\end{tikzpicture}
+	\end{center}
+	The pole that touches the magnetic object first will be the pole of that magnetic object at that point.
+
+	For the electromagnet, refer to chapter 21.
+
+	\subsubsection{Demagnetisation}
+	To demagnetise a magnet you first have to orient it in the \textbf{east-west direction}. Then there are three ways to do this.
+	\begin{enumerate}
+		\item \textbf{Hammering:} Hammering a magnet placed in the east-west direction alters the alignment of the magnetic domains, causing the magnet to lose its magnetism.
+		\item \textbf{Heating:} Strongly heating a magnet and letting it cool in an east-west orientation will cause the magnet to lose its magnetism. The temperature to heat the magnet up to such that the atoms lose the magnetism is called the Curie temperature.
+		\item \textbf{Electrical Method:} Place a magnet in a solenoid in the east-west direction and connect an alternating current supply. Withdraw the magnet while the alternating current is flowing in the solenoid until it is some distance away.
+	\end{enumerate}
+
+	\subsection{Magnetic Fields}
+	\pdef{Magnetic Field}{A magnetic field is the region surrounding a magnet, in which a body of magnetic material experiences a magnetic force.}
+
+	Magnetic field lines \textbf{cannot cross}.
+
+	The magnetic field of a magnet can be plotted by sprinkling iron filings around it, or plotting it with a plotting compass.
+
+	To use a plotting compass, align a magnet in the north-south direction first. Then using a plotting compass, from the north pole of the magnet, draw a point at where the compass points to. Then continue this and connect the lines. Remember that plotting compasses point in the direction of the field lines.
+
+	For attraction and repulsion of two magnetic poles use this lovely diagram that I could not draw so I had to source it online.
+	\begin{center}
+		\includegraphics[width=0.85\linewidth]{graphics/magnetismFieldLines}\footnote{phys.libretexts.org}
+	\end{center}
+
+	\subsection{Temporary and Permanent Magnets}
+	Magnetic materials can either be ``soft'' or ``hard''. An example of a soft magnetic material is iron. An example of a hard magnetic material is steel.
+	\begin{itemize}
+		\item \textbf{Magnetisation} \begin{itemize}
+			\item Hard magnetic materials are difficult to magnetise and demagnetise.
+			\item Soft magnetic materials are easier to magnetise and demagnetise.
+		\end{itemize}
+		\item \textbf{Uses} \begin{itemize}
+			\item Hard magnetic materials are used to make permanent magnets.
+			\item Soft magnetic materials are used to make temporary magnets.
+		\end{itemize}
+		\item \textbf{Interaction with Field Lines} \begin{itemize}
+			\item Hard magnetic materials do not allow magnetic fields to pass through it as easily as soft magnetic materials.
+			\item Soft magnetic materials allow magnetic fields to pass through it with ease.
+		\end{itemize}
+	\end{itemize}
+\end{document}

main.tex

@@ -130,6 +130,7 @@ \part{Electricity and Magnetism}
 \subfile{content/chapter17}
 \subfile{content/chapter18}
 \subfile{content/chapter19}
+\subfile{content/chapter20}
 \end{multicols*}
 
 \end{document}