physics notes

MAXWELL Gauss’s Electric Law : Gauss’s Magnetic Law :

Faraday Induction Law:

Ampère’s Law (with Maxwell’s correction)

inductance

.

LR circuits

voltage drop across an inductor:

ENM — DIPOLES:

Gauss’s Law Note that this is not actually a law, it’s just a corollary of Coulomb’s Law. Electric flux through a closed surface is equal to enclosed charge over .

• Electric field lines tell you where a positive test charge would go
• Dipole moment points from negative charge to positive charge
  • this makes sense, because the general principle is that we give priority to positive dudes and let negative dudes flip signs.

slit experiments

Double slit ok we’re going to make an approximation: , so we can assume that the angle of the ray from either slit to some point on the wall is roughly the same. Fine. Let’s fix some point on the wall and suppose that rays from the slits going to point have angle (above the horizontal) of approximately .

Then, if you wanted one of the waves to travel an extra wave-length versus the other, you’d get constructive interference whenever satisfies

And the separation between peaks is

You’d get destructive interference when satisfies

Single slit MINIMA at where is width of slit.

BOTH i.e. you have two slits but they aren’t negligibly thin. Then you just combine both cases; good luck.

Stefan Boltzman Law — Hot stuff emits EM waves.

Note:

Time average of Ponyting Vector gives intensity of EM wave!!

Note poynting vector

Radiation pressure: time avg of ponyting vector OVER c Prad = S/c

ENERGY density

In vacuum these two terms are the same.

Ah so radiation pressure is the same as energy density — weird.