deletions | additions       diff --git a/The_discrete_energy_levels_can__.tex b/The_discrete_energy_levels_can__.tex  index b74f115..7cbfdd1 100644  --- a/The_discrete_energy_levels_can__.tex  +++ b/The_discrete_energy_levels_can__.tex 
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The distance the electron travels before colliding with an atom and exciting it is called the mean free path. Electrons gain additional accelerating energy as the number of inelastic collision is increasing, which can explain why the spacing between two anode voltage minima is increasing as shown in the figure. (NEED A FIGURE OF OUR PLOT AND I DON'T KNOW WHY THE SPACING IS INCREASING IN THIS WAY). The mean free path can be calculated using the equation below:  $$\lambda=\frac{L}{2E_{a}}\frac{d\Delta E(n)}{dn}$$  where $\lambda$ is the mean free path, L is the distance between accelerating grid and control grid, $\Delta E(n)$ is the spacing between two minima in Franck Hertz experiment, n is the minimum order, $E_{a}$ is the lowest excitation energy.  More stuff to discuss...  \begin{itemize}  \item mean free path + equations