Solid State Electronic Devices, 7th Edition

2.1 Introduction to Physical Models

The main effort of science is to describe what happens in nature, in as complete and concise a form as possible. In physics this effort involves observing natural phenomena, relating these observations to previously established theory, and finally establishing a physical model for the observations. For example, we can explain the behavior of a spring-supported weight moving up and down periodically after an initial displacement, because the differential equations describing such a simple harmonic motion have been established by Newtonian classical mechanics.

When a new physical phenomenon is observed, it is necessary to find out how it fits into the established models and “laws” of physics. In the vast majority ...