Ch. 15 Quantum Theory
The Photoelectric Effect E=hf
Quantization- the natural world is granular rather than smoothly continous
Quantum- any elemental particle that makes up matter or carries energy
The photoelectric effect is a model for how matter radiates
hypothesized by Max Plank in 1900s
warm bodies emit radiant energy in individual budles called quanta
energy in each quantum is proportional to the frequency of radiation
Frequency of light
low frequency light does not eject electrons
high frequency light does eject electrons
Einstein viewed light as a stream of particles, photons interact with matter one at a time, and high energy photons dislodge electrons from certain metals
Types of Light Excitation
What is Fluorescence?
material excited by ultraviolet light emit visible light upon de-excitation
How do fluorescent lamps work?
Electrons are emitted from filaments and strikes mercury that then releases an UV photon that strikes the inner phosphorus lining inside the lamp and produce a white lamp
What is incandescence?
frequency of radiation emitted from a hot body
peak frequency is proportional to the temperature
Electron diffraction
What are lasers?
Lasers are coherent beam of light rays that have the same frequency and are in phase
Incoherent light- light waves out of phase and different frequencies)
Monochromatic light- same light wave frequency but are out of phase
LASERS ARE NOT A SOURCE OF ENERGY
According to Louise de Broglie- a particles wavelength is related to their momentum; wavelength =h/mv
electron waves orbiting a nucleus form standing waves
Wave-Particle Duality
A photon acts like a particle when emitted by an atom, but behaves like a wave when traveling
uncertainty principle (only applies to quantum mechanics) states that at atomic an subatomic realm, position and motion are uncertain to predict
uncertainties in measurement of momentum and position when multiplied must be equal to or greater than planks constant
uncertainties in the measurements of time and energy when multiplied must be equal to or greater than planks constant
correspondence theory- introduced by Niels Bohr that states the new theory and old must correspond
complementary- accepting alternate explanations for natural phenomena
What is phosphorescence?
electrons are excited and "bounce" or are de-excited from traveling between energy levels
electrons getting excited and when getting de-excited, the electron gets "stuck" at an energy level then returns to its ground state.
electrons getting excited and when getting de-excited, the electron gets "stuck" at an energy level then returns to its ground state.