Alisha Vira edited The_distance_the_electron_travels__.tex  over 8 years ago

Commit id: 2d3abe1425e82504566adf2fa0731577aea444a2

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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.  As the applied accelerating voltage increases, electrons continue to gain energy along their mean free path and could possibility also excite the higher energy levels of the atoms. Since electrons gain additional accelerating energy as the number of inelastic collision increase, this means that if an electron inelastically collides twice with atoms their total energy gained is $$E_2=2E_a+2\delta_2$$. For n inelastic collisions, the total energy gained by an electron can be expressed as below:   $$E_n=n(E_a+\delta_n) \text where \text{where}  \delta_n=n\frac{n}{L}E_a$$. The two equations above can be used to derive an expression for the spacing between two minimas (refer to Appendix A). The expression $\Delta E(n)=[1+\frac{n}{L}(2n-1)]E_a$ shows that the spacing between two anode voltage minima is increasing.