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Diffstat (limited to 'ediffract_new.tex')
| -rw-r--r-- | ediffract_new.tex | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/ediffract_new.tex b/ediffract_new.tex index 8ace7bf..5e727c6 100644 --- a/ediffract_new.tex +++ b/ediffract_new.tex @@ -35,7 +35,7 @@ \begin{figure}[h] \centering -\includegraphics[width=\textwidth]{./pdf_figs/ed1_new} \caption{\label{ed1}Electron +\includegraphics[width=0.6\textwidth]{./pdf_figs/ed1_new} \caption{\label{ed1}Electron Diffraction from atomic layers in a crystal.} \end{figure} \section*{Theory} @@ -88,7 +88,7 @@ electron diffraction tube, make sure these connections are well-protected and cannot be touched by accident while taking measurements. \begin{figure}[h] \centering -\includegraphics[width=6in]{./pdf_figs/ed2} \caption{\label{ed2}Electron Diffraction Apparatus.} +\includegraphics[width=5in]{./pdf_figs/ed2} \caption{\label{ed2}Electron Diffraction Apparatus.} \end{figure} \subsection*{Setup} @@ -126,9 +126,9 @@ Anode Current & $I_A$& 0.15 mA at 4000 V ( 0.20 mA max.) \item Slowly increase $V_a$ until you observe two rings appear around the direct beam. Slowly change the voltage and determine the highest achievable accelerating voltage, and the lowest voltage when the rings are visible. -\item Measure the diffraction angle $\theta$ for both inner and outer rings for 5-10 voltages from that range, -using the same thin receipt paper (see procedure below). Each lab partner should -repeat these measurements (using an individual length of the thin paper). +\item Measure the diffraction angle $\theta$ for both inner and outer rings for 8-10 voltages from that range, +using the same strip of a masking tape (see procedure below). +\item Turn the voltage down, take a new masking tape and repeat the measurement procedure, using the same values of $V_a$ at least two more times. \item Calculate the average value of $\theta$ from the individual measurements for each voltage $V_a$. Calculate the uncertainties for each $\theta$. \end{enumerate} @@ -150,10 +150,10 @@ where the distance between the target and the screen $L = 0.130$~m is controlled The ratio between the arc length $s$ and the radius of the curvature for the screen $R = 0.066$~m gives the angle $\phi$ in radians: $\phi = s/2R$. To measure $\phi$ carefully place a piece of -thin receipt paper on the tube so that it crosses the ring along the diameter. +a masking tape on the tube so that it crosses the ring along the diameter. Mark the position of the ring for each accelerating voltage, and then remove the paper and measure the arc length $s$ corresponding to -each ring. You can also make these markings on masking tape placed gently on the tube. +each ring. \begin{figure} |