The first excited state of a particular atom in a gas is 5.8 eV above the ground state. A moving electron collides with one of these atoms, and excites the atom to its first excited state. Immediately after the collision the kinetic energy of the electron is 3.7 eV. What was the kinetic energy of the electron just before the collision? Ki = eV

E₀ = 9.5 eV

Explanation:

In the processes of absorption, excitation and shocks the energy must be conserved therefore the energy before the shock is

         E₀ = E_excitation + E_residual

         E₀ = 5.8 + 3.7

         E₀ = 9.5 eV

this is the energy of the electron before the collision

total distance/total time

(85 + 82)/(5+3)

167/8

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