The Bohr Atom
BohrComestoCambridge
In 1911, the 26-year-old Niels Bohr earned a Ph. D. at the University of Copenhagen; his
dissertation was titled "Studies on the Electron Theory of Metals". He was awarded a
postdoctoral fellowship funded by the Carlsber
Special Relativity: Synchronizing Clocks
Suppose we want to synchronize two clocks that are some distance apart.
We could stand beside one of them and look at the other through a telescope, but wed
have to remember in that case that we are seeing the cloc
Special Relativity
GalileanRelativityagain
At this point in the course, we finally enter the twentieth centuryAlbert Einstein wrote
his first paper on relativity in 1905. To put his work in context, let us first review just
what is meant by relativity in
From Bohr's Atom to Electron Waves
ReactionstoBohr'sModel
Bohr's interpretation of the Balmer formula in terms of quantized angular momentum was
certainly impressive, but his atomic model didn't make much mechanical sense, as he
himself conceded. For exam
Evolution of the Atomic Concept and the Beginnings of
Modern Chemistry
EarlyGreekIdeas
The first "atomic theorists" we have any record of were two fifth-century BC Greeks,
Leucippus of Miletus (a town now in Turkey) and Democritus of Abdera. Their theorie
Kinetic Theory of Gases: A Brief Review
Bernoulli'sPicture
Daniel Bernoulli, in 1738, was the first to understand air pressure from a molecular point
of view. He drew a picture of a vertical cylinder, closed at the bottom, with a piston at the
top, the pi
Spectra
EarlyWork
The first person to realize that white light was made up of the colors of the rainbow was
Isaac Newton, who in 1666 passed sunlight through a narrow slit, then a prism, to project
the colored spectrum on to a wall. This effect had been n
The Michelson-Morley Experiment
TheNatureofLight
As a result of Michelsons efforts in 1879, the speed of light was known to be 186,350
miles per second with a likely error of around 30 miles per second. This measurement,
made by timing a flash of light tr
Wave Equations
PhotonsandElectrons
We have seen that electrons and photons behave in a very similar fashionboth exhibit
diffraction effects, as in the double slit experiment, both have particle like or quantum
behavior. We can in fact give a complete anal
The Speed of Light
EarlyIdeasaboutLightPropagation
As we shall soon see, attempts to measure the speed of light played an important part in
the development of the theory of special relativity, and, indeed, the speed of light is
central to the theory.
The
Frames of Reference and Newtons Laws
The cornerstone of the theory of special relativity is the Principle of Relativity:
The Laws of Physics are the same in all inertial frames of reference.
We shall see that many surprising consequences follow from this