Question

Simplified model of electron energy levels for a cartain atom is shown in figure. The atom is bombarded will fast moving electrons. The impact of one of these electrons can cause the removal of electron from K-level , thus, creating a vacancy in the K-level. This vacancy in K-level is filled by an electron from l-level and the energy reased in this transition can either appear as electromagnetic waves or may all be used knock out an electron from M-level of the atom.

Based on above information, answer the following question:
The minimum potential difference through which bombarding electron beam must be acclerated from rest to cause the ejection of electron from K-level is.
A. `18750 V`
B. `400 kV`
C. `16 kV`
D. `21.6 kV`

Answer 1

Correct Answer - A
The minimum enegry required to remove the electron from `K`- level is `3 xx 10^(-15) J`.
Let `V` be the potential difference required , then
`eV = 3 xx 10^(-15) J`.
`V = (3 xx 10^(-15))/(1.6 xx 10^(-16)) = 18750 V`