Franck-Hertz Experiment

In an attempt to jump over the distance between me and my student friends and record the snap of my lectures at least less fleetingly through fleeting space-time, I am posting here snapshots of the blackboard presentation in my lectures. These lectures are not as great as and as famed as the great Feynman lectures and limitations are there imposed by the so called syllabus-test-exam-mark frame work, yet they might be useful in instigating a love of physics in young minds. 
As Great Galileo once said one can't teach anybody anything but certainly endeavor to make him feel that and love that which he/her teaches.
Lot of words makes things a little bit more boring but they also make them a bit more clear. 

Here is a snapshot of my lecture on Franck-Hertz Experiment which conclusively proved the existence of discrete energy structure in atoms hence historically important: