## Summary

This lecture will first briefly summarize the Principle of Least Action from Classical Mechanics. Then we will discuss the Electric Form Factor integral, which is derived as a correction to the Rutherford Scattering Formula. This integral essentially provides a way to describe diffraction patterns from wave interference.

With the development of these tools, we will present the Feynman path integral and try to understand the motivations behind the integral from a qualitative perspective, one which is accessible to undergraduate students. Finally, we will see how the Feynman path integral successfully recovers the Principle of Least Action on a large (relative to hbar) distance scale, thus generalizing classical mechanics.