What I Learnt Today

In Physics of Semiconductor Devices, I learnt that dopant atoms can, depending on their valence electrons, either donate electrons or holes. And that a hole is a fancy word for lack of electron. One interesting question is raised, that when a silicon host is doped with, say, phosphorus atoms, which replace some silicon atoms from their original sites, where do the original silicon atoms go?


In Effective Reading, I learnt from a 1963 article that Japanese students have a hell of a life thanks to a plethora of entrance exams, to qualify them into kindergarten, school, college, university and eventually the workplace.


In Applied Spectroscopy, I learnt that blue lasers are easier to manufacture compared to red lasers. But due to blue light waves having a shorter wavelength, and hence a higher energy, we are more familiar with the red laser in daily use.




In Solid State Physics I, I learnt that any object rotated 360 degrees and maintains its original appearance after the rotation, is symmetrical. No kidding!