Neap 2018 exam analysis & cheatsheet

diff --git a/physics/exam-analysis.xlsx b/physics/exam-analysis.xlsx
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diff --git a/physics/final.pdf b/physics/final.pdf
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diff --git a/physics/final.tex b/physics/final.tex
index 1db6640019b9d718215d93388e5e256d4307b714..9a64a9d6f0fa7e79b760a9d24325f5cb4bd1f027 100644 (file)
--- a/physics/final.tex
+++ b/physics/final.tex
@@ -190,9 +190,11 @@
 % -----------------------
   \subsection*{Energy and work}
 
 % -----------------------
   \subsection*{Energy and work}
 

+  Total energy = mass energy
+

     $E_{\text{rest}} = mc^2, \quad E_K = (\gamma-1)mc^2$
 
     $E_{\text{rest}} = mc^2, \quad E_K = (\gamma-1)mc^2$
 

-    $E_{\text{total}} = E_K + E_{\text{rest}} = \gamma mc^2$
+    $E_{\text{total}} = \gamma E_{\text{rest}} = E_K + E_{\text{rest}} = \gamma mc^2$

 
     $W = \Delta E = \Delta mc^2=(\gamma-1)m_{\text{rest}} c^2$
 
 
     $W = \Delta E = \Delta mc^2=(\gamma-1)m_{\text{rest}} c^2$
 


@@ -249,18 +251,18 @@
 
     \[v=\sqrt{GM \over r} = \sqrt{gr} = {{2 \pi r} \over T}\]
 
 
     \[v=\sqrt{GM \over r} = \sqrt{gr} = {{2 \pi r} \over T}\]
 

-    \[T={\sqrt{4 \pi^2 r^3 \over {GM}}}\tag{period}\]
+    \[T={\sqrt{4 \pi^2 r^3 \over {GM}}}=2 \pi \sqrt{r_{\text{alt}} \over g_{\text{alt}}}\tag{period}\]

 
     \[r = \sqrt[3]{{GMT^2}\over{4\pi^2}}\tag{radius}\]
 
 % -----------------------
   \subsection*{Magnetic fields}
 
     \[r = \sqrt[3]{{GMT^2}\over{4\pi^2}}\tag{radius}\]
 
 % -----------------------
   \subsection*{Magnetic fields}

-    \begin{itemize}
-      \item field strength $B$ measured in tesla
-      \item magnetic flux $\Phi$ measured in weber
-      \item charge $q$ measured in coulombs
-      \item emf $\mathcal{E}$ measured in volts
-    \end{itemize}
+    % \begin{itemize}
+    %   \item field strength $B$ measured in tesla
+    %   \item magnetic flux $\Phi$ measured in weber
+    %   \item charge $q$ measured in coulombs
+    %   \item emf $\mathcal{E}$ measured in volts
+    % \end{itemize}

 
     % \[{E_1 \over E_2}={r_1 \over r_2}^2\]
 
 
     % \[{E_1 \over E_2}={r_1 \over r_2}^2\]
 


@@ -290,6 +292,8 @@
 
     \textbf{Right hand grip:} thumb points to $I$ (single wire) or N (solenoid / coil)
 
 
     \textbf{Right hand grip:} thumb points to $I$ (single wire) or N (solenoid / coil)
 

+    \textbf{Magnet through ring:} consider $g$
+

     \includegraphics[height=2cm]{graphics/slap-2.jpeg}
     \includegraphics[height=3cm]{graphics/grip.png}
 
     \includegraphics[height=2cm]{graphics/slap-2.jpeg}
     \includegraphics[height=3cm]{graphics/grip.png}
 


@@ -303,6 +307,8 @@
 
     \textbf{Xfmr} core strengthens \& focuses $\Phi$
 
 
     \textbf{Xfmr} core strengthens \& focuses $\Phi$
 

+    \columnbreak
+

 % -----------------------
   \subsection*{Particle acceleration}
 
 % -----------------------
   \subsection*{Particle acceleration}
 


@@ -311,6 +317,7 @@
     e- accelerated with $x$ V is given $x$ eV
 
     \[W={1\over2}mv^2=qV \tag{field or points}\]
     e- accelerated with $x$ V is given $x$ eV
 
     \[W={1\over2}mv^2=qV \tag{field or points}\]

+    \[V_{\text{point}} = (V_1 - V_2) \div 2 \tag{if midpoint} \]

     \[v=\sqrt{{2qV} \over {m}}\tag{velocity of particle}\]
 
     Circular path: $F\perp B \perp v$
     \[v=\sqrt{{2qV} \over {m}}\tag{velocity of particle}\]
 
     Circular path: $F\perp B \perp v$


@@ -331,14 +338,13 @@
       {\item Series $V$ shared within branch}
     \end{itemize}
 
       {\item Series $V$ shared within branch}
     \end{itemize}
 

-    \includegraphics[height=4cm]{graphics/ac-generator.png}
-

 % -----------------------
   \subsection*{Motors}
 % \begin{wrapfigure}{r}{-0.1\textwidth}
 
     \includegraphics[height=4cm]{graphics/dc-motor-2.png}
 % -----------------------
   \subsection*{Motors}
 % \begin{wrapfigure}{r}{-0.1\textwidth}
 
     \includegraphics[height=4cm]{graphics/dc-motor-2.png}

-    \includegraphics[height=3cm]{graphics/ac-motor.png} \\
+    % \includegraphics[height=3cm]{graphics/ac-motor.png} \\
+    \includegraphics[height=4cm]{graphics/ac-generator.png} \\

 
     Force on I-carying wire, not Cu \\
     $F=0$ for front & back of coil (parallel) \\
 
     Force on I-carying wire, not Cu \\
     $F=0$ for front & back of coil (parallel) \\


@@ -439,7 +445,7 @@
   \subsection*{Refraction}
   \includegraphics[height=3.5cm]{graphics/refraction.png}
 
   \subsection*{Refraction}
   \includegraphics[height=3.5cm]{graphics/refraction.png}
 

-  When a medium changes character, light is \emph{reflected}, \emph{absorbed}, and \emph{transmitted}. $\lambda$ changes, not $f$.
+  When a medium changes character, light is \emph{reflected}, \emph{absorbed}, and \emph{transmitted}. $\lambda$ changes, not $f$. $n$ changes slightly with $f$ (dispersion)

 
   angle of incidence $\theta_i =$ angle of reflection $\theta_r$
 
 
   angle of incidence $\theta_i =$ angle of reflection $\theta_r$
 


@@ -549,7 +555,7 @@ $f \cdot V$ & ${h \over q}$ & $f_0$ & $-\phi \over q$ &
     \item $E$ and $f$ of photon: $E_2 - E_1 = hf = {hc \over \lambda}$
     \item Ionisation energy - min $E$ required to remove e-
     \item EMR is absorbed/emitted when $E_{\operatorname{K-in}}=\Delta E_{\operatorname{shells}}$ (i.e. $\lambda = {hc \over \Delta E_{\operatorname{shells}}}$)
     \item $E$ and $f$ of photon: $E_2 - E_1 = hf = {hc \over \lambda}$
     \item Ionisation energy - min $E$ required to remove e-
     \item EMR is absorbed/emitted when $E_{\operatorname{K-in}}=\Delta E_{\operatorname{shells}}$ (i.e. $\lambda = {hc \over \Delta E_{\operatorname{shells}}}$)

-    \item No. of lines - include all possible states
+    \item No. of lines - include all possible states. \Delta E \ne |\Delta E|

   \end{itemize}
 
   \subsection*{Uncertainty principle}
   \end{itemize}
 
   \subsection*{Uncertainty principle}


@@ -562,8 +568,8 @@ $f \cdot V$ & ${h \over q}$ & $f_0$ & $-\phi \over q$ &
 
   \subsubsection*{wave model}
   \begin{itemize}
 
   \subsubsection*{wave model}
   \begin{itemize}

-    \item cannot explain photoelectric effect
-    \item $f$ is irrelevant to photocurrent
+    % \item cannot explain photoelectric effect
+    \item any $f$ works, given $t$

     \item predicts delay between incidence and ejection
     \item speed depends on medium
     \item supported by bright spot in centre
     \item predicts delay between incidence and ejection
     \item speed depends on medium
     \item supported by bright spot in centre


@@ -573,9 +579,10 @@ $f \cdot V$ & ${h \over q}$ & $f_0$ & $-\phi \over q$ &
   \subsubsection*{particle model}
 
   \begin{itemize}
   \subsubsection*{particle model}
 
   \begin{itemize}

-    \item explains photoelectric effect
+    % \item explains photoelectric effect

     \item rate of photoelectron release $\propto$ intensity
     \item no time delay - one photon releases one electron
     \item rate of photoelectron release $\propto$ intensity
     \item no time delay - one photon releases one electron

+    \item threshold frequency

     \item double slit: photons interact. interference pattern still appears when a dim light source is used so that only one photon can pass at a time
     \item light exerts force
     \item light bent by gravity
     \item double slit: photons interact. interference pattern still appears when a dim light source is used so that only one photon can pass at a time
     \item light exerts force
     \item light bent by gravity