deletions | additions       diff --git a/The_discrete_energy_levels_can__.tex b/The_discrete_energy_levels_can__.tex  index a88cd20..449a0f8 100644  --- a/The_discrete_energy_levels_can__.tex  +++ b/The_discrete_energy_levels_can__.tex 
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[The discrete energy levels can be explained by elastic and inelastic collisions between the electrons and the neon or argon atoms. When the accelerating voltage applied to the cathode is above a certain point, the Franck-Hertz experiment found that there are no longer only elastic collisions. The inelastic collisions occur once the electron has enough energy to excite the atom.] <-- should i remove? is this repeated?   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 increasing.(  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 and $E_{a}$ is the lowest excitation energy.