91Ó°ÊÓ

In the figure 39-9 the initial energy of electron is 106 eV. It absorbs addition 400eV of energy from an external source. Total energy is the sum of these two energies.

$E_{total}=K_j+E\text{'}$

Here, $E_{{}_{total}}$is the total energy of the electron after absorbing energy from the external

is the initial energy possessed electron, and E' is the external absorbed by the electron.

Substitute 106eV for $K_i$for and 400 eV to find $E_{total}$

$$\begin{gathered} E_{total}=106eV+400eV \\ =506eV \end{gathered}$$

Thus, the total energy of the electron after absorbing energy from the external source

The total energy possessed by the electron exceeds the finite potential energy of the well thus, the electron moves to the regions x > L

the kinetic energy of the electron in the regions and is the external absorbed by x > L is,

$K=E_{total}-U_{well}$

Here, k is the kinetic energy of the electron in the region x > L

And $U_{well}$ is he potential energy of the well.

Substitute 506eV for $E_{total}$and 450eV for $U_{well}$ to find k.

K = 506 eV - 450 eV

=56eV

Thus, the electron kinetic energy after this absorption assuming that the electron moves to a position for which x > L is 56 eV