Absorption
If the radiation travels through a medium which absorbs (or
scatters) radiation, the energy in the beam will be reduced:
In
In+dIn
dA
dS
Number density of absorbers (particles per unit volume) = n
Each absorber has cross-sectional area = sn (un

Cyclotron and synchrotron radiation
Electron moving perpendicular to a magnetic
field feels a Lorentz force.
Acceleration of the electron.
Radiation (Larmors formula).
Define the Lorentz factor: g
1
1- v 2 c 2
Non-relativistic electrons: (g ~ 1) - cyclot

Sources of radiation
Most important type of radiation is blackbody radiation. This is radiation that is in thermal equilibrium with matter at some temperature T. Lab source of blackbody radiation: hot oven with a small hole which does not disturb thermal

Stellar structure
For an isolated, static, spherically symmetric star, four basic
laws / equations needed to describe structure:
Conservation of mass
Conservation of energy (at each radius, the change in
the energy flux equals the local rate of energy r

Review: Particle in rigid 3D box
Today:
Rest of the 3D rigid box
The Hydrogen atom
h2 2 2 2
( x, y, z) + V ( x, y, z) ( x, y, z) = E ( x, y, z)
+
+
2m x2 y 2 z 2
V(x,y,z) = 0 inside; outside.
Final Exam is on Wednesday, Dec. 14,
1:30pm-4pm in G1B20 (