Slide 1
1642
1642
1801
Newton
Newton
Young
Maxwell
Balmer
J.J. Thompson
1889
1865
1885
Planck
1901
Einstein
1905
Rutherford
1911
1913
Bohr
1915
1917
Einstein
Proof
Proof of
of SR
SR
De Broglie
1923
Nuclear Physics
Slide 2
What Newton Gave Us……………………..
Space
“ Absolute space, in its own nature, without relation to anything external,
remains always similar and immovable.”
Time
“Absolute, true, and mathematical time, of itself, and from its own nature,
flows equably without relation to anything external, and by another name
is called duration.”
Causality
Newton’s third law –
For every action there is an equal and opposite reaction.
Particles
Light is a particle
No insight into atomic structure
Slide 3
What Newton Didn’t Give Us……………………
How do objects which interact with each
other exchange information?
What is the “medium of exchange?
Action at a distance?
Slide 4
Modern Physics
- Relativity
- Quantum Mechanics
- Nuclear Physics
- Structure of the Atom
Slide 5
J. Balmer - Solar Spectra
J.J. Thompson - Discovers electron
A.A. Michelson - Speed of Light / Ether
M. Planck - Blackbody Radiation / Quanta
A. Einstein - Photoelectric Effect / Relativity / Brownian Motion
E. Rutherford - Structure of Atom
N. Bohr - Bohr Model of the Atom
L. De Broglie - Wave Nature of Matter
Slide 6
Michelson’s intent was to:
1.) Measure the speed of light.
2.) Detect the presence of the ether by detecting
differences in the speed of light.
He referred to his results as the most famous
non-result in history.
Slide 7
His idea was to detect the change
in the speed of light by comparing
two beams of light which passed
through the ether at right angles to
each other.
Lorentz concluded that the ether
actually had a contracting effect on
the apparatus and calculated the
effect as,
L = Lo (1- v2/c2)1/2 , the Lorentz
contraction.
Slide 8
Slide 9
Planck’s solution was the development of quantized
(restricted) values of energy in a mechanical
oscillation scheme (E = hν), 1901.
Further developed by Einstein in the photo-electric
Effect, 1905.
Rutherford, 1911 atomic model
(Gieger and Marsden)
Bohr model of the atom, 1913.
Slide 10
Structure of Atom
- 99.99% space
- very dense nucleus
- electrons orbit outside the nucleus
Problems
Electric attraction between proton and
electron = 4.6 X 10-18 Newtons !
So the acceleration of the electron
toward the proton is 25 X 1012 m/s2
Time of flight = 10-12 seconds
Slide 11
Bohr Model of Atom
- Stable Orbits for Electrons
- Transitions between Orbits Allowed
- Requires a change in energy
- Orbital sizes based on angular momentum
2πr = nh/mv
or
mvr = nh/2π
Explains
- stability of matter
- line spectra
- emission
- absorption
- hydrogen atom
(ionization energy, ground state radius, Rydberg constant)
Slide 12