Early Quantum Theory and Models of the Atom

Discovery of Electron

Cathode Rays

e/m measurement

kgCm

erB

E

m

e

/1076.1

;

11

2

Oil-Drop Experiment to find e

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

KmTp 3109.2

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:

sJh

hfE

34

min

106.6

;

Planck’s Quantum Hypothesis

Planck’s assumption suggests that the energy of any molecular vibration could be only some whole number multiple of hf:

....3,2,1

;min

n

nhfE