Summary: Things I learn in Electrodynamics II

This is going to be my only entry in the next 3 days!! I swear!! unless something unexpected happen~~ By the end of the day, I will have 30 points listed here!! so that I won't forget everything later on~~

1. Snell's law is a statement of conservation of linear momentum (parallel to the interface)
2. "Physical explanation of Fourier Transform" -- To resolve a point, you need the whole range of spatial frequencies k. In practice, k = 2*pi/lamda = omega / v, where v = c/n is the wave speed. There is a maximum achievable k, and so we can no longer resolve a point. Instead we can only see clearly something of finite size. This maximum achievable k is proportional to the angular frequency of the light waves used. kx^2+ky^2+kz^2 = k^2. If somehow we can make kz^2 negative, the maximum kx and ky are increased, so that resolving power increases.
3. Evanescent waves are decaying waves that can be, and are actually being used, to increase the resolving power of optical microscope, using the above idea. (which is known as near-field microscopy)
4. Exactly the same idea is employed again with the use of surface plasmons
5.