Transcript Holography

Holography
Early Quantum Theory and
Models of the Atom
Discovery of Electron
Cathode Rays
e/m measurement
E
e
 2 ;
m B r
e
11
 1.76  10 C / kg
m
Oil-Drop Experiment to find e
Thomson’s Model
Rutherford’s Model
Blackbody Radiation
All objects emit radiation whose total
intensity is proportional to the fourth
power of the Kelvin temperature.
A blackbody is a body that would absorb all
the radiation falling on it.
Wien’s Law
3
 pT  2.9  10 m  K
The Sun’s Surface Temperature
Estimate the temperature of the surface of our Sun, given
that the Sun emits light whose peak is in the visible
spectrum at around 500 nm.
Star Color
Suppose a star has a surface temperature of
32,500 K. What color would this star appear?
Energy distributed among the oscillating electric
charges of the molecules is not continuous, but
instead consists of a finite number of very small
discrete amount, each related to the frequency of
oscillation as:
Emin  hf ;
h  6.6  10
34
J s
Planck’s Quantum Hypothesis
Planck’s assumption suggests that the energy of any
molecular vibration could be only some whole number
multiple of hf:
Emin  nhf ;
n  1,2,3....
Baby-Quiz
1. Why are diffraction effects of your eyes more important during
the day than at night?
2. Will the converging lens focus blue light or red light at a closer
distance to the lens? Explain.
3. Assume that you have the thinnest film that strongly reflects
red light. Would you need to make the film thinner or thicker to
completely reflect blue light? Explain.
4. If all the labels had come off the sunglasses in the drug store,
how could you tell which ones were polarized?