Wave-Particle Duality

All matter can exist in the form of a wave or as a particle. Specific experiments have been used to prove this.

Answer Me!!!

Is light a wave or a particle? Justify your answer with specific proof.

Wave or Particle….OR Both?

Examples of wave behavior Reflection Refraction Diffraction Interference Polarization

Examples of particle behavior Reflection Refraction Photoelectric Effect

The Photoelectric Effect

If light consists of tiny particles called “photons” then these particles will be able to interact with other particles.

Results of the Photoelectric Effect The electrons were emitted immediately - no time

lag! Increasing the intensity of the light increased the

number of photoelectrons, but not their maximum kinetic energy!

Red light will not cause the ejection of electrons, no matter what the intensity!

A weak violet light will eject only a few electrons, but their maximum kinetic energies are greater than those for intense light of longer wavelengths!

Photoelectric Effect Equation

The results show that the Energy of the electron emitted due to the photoelectric effect was directly proportional to the frequency of light incident on the material.

E=hfE is Energy

h is Planck’s constant (6.63 x 10-34 Js)

f is frequency

Practice Problem

A green laser with a wavelength of 580 nm is shining on a photosensitive surface. How much energy (in electronvolts) is transferred from the photons to the electrons in the material?