Pre-Quantum Theory

Maxwell A change in a electric field produced a magnetic field A change in a magnetic field produced an electric field

Light Transmission Light propagated as a wave.

Older Wave Theory: Some things are unexplainable with older wave theory: 1. Wave theory could not explain why a hot body emitted light. 2.UV-light discharged electrically- charged metal plates (the photoelectric effect).

Quantum Theory

Max Planck The energy of vibration of the atoms in a solid could have only specific frequencies

Max Planck E = nhf f=frequency of vibration h=constant {7 x J/Hz} n=integer (0,1,2,3,etc.)

Max Planck This is said to be quantized energy.

Electrons are emitted from a negatively charged metal plate with a potential difference when UV-light falls on it.

A)Only radiation above the threshold frequency (f 0 )ejects electrons no matter what intensity the light. B)Photon- electromagnetic radiation travels in packets with a given amount of energy based on the frequency of the radiation. [Einstein] E = hf

EM radiation has properties of particles. KE = hf - hf o Think conservation of energy.

This is going to be KE max of an electron since hf o is the minimum energy needed to free an electron (assuming it is freeing a higher energy electron).

hf 0 is the energy needed to free the electron and will not accumulate. One photon interacts with one electron.

A known frequency of X-ray were directed at a graphite block, some scattered X-rays were found to have lower frequencies (increased wavelength). Therefore, they lost energy & momentum in collisions.

Louis Victor de Broglie materials have wave properties =h=h p mv

Beams of electrons shot through a crystal showed diffraction grating patterns similar to those of X-rays with similar wavelength.

located at one point in space Particle Wave frequency, wavelength, amplitude can occupy same space at the same time with losing energy can travel through solid objects continuous space needed to make a wave have mass, size, KE, & momentum can not travel through solid objects (cannot occupy same space at same time)

Beams of electrons shot through a crystal showed diffraction grating patterns similar to those of X-rays with similar wavelength.