Wave-Particle Duality

Question 1

Light behaves as a wave in…

Answer 1

…interference and in diffraction. These can only be explained by waves interfering constructively (when two waves overlap in phase) or interfering destructively (when two waves are out of phase)

Question 2

Light behaves as a particle in the…

Answer 2

…Photoelectric effect.
- Einstein explained photoelectricity experiments by thinking of a beam of light as a series of particle like “photons”.
- If a photon is a discrete bundle of energy then it can interact with an electron in a one-to-one way.

Neither Wave Theory nor the Particle Theory describe what light actually is, they are just two different models that help explain how light behaves.

Question 3

Transmission Electron Microscope

Answer 3

A very thin specimin is used and the parts of the beam that pass through the specimin is projected onto a screen to form an image.

Question 4

Scanning Tunneling Microscope

Answer 4

Uses principles of quantum mechanics.
- Fine probe moved over surface of the sample and voltage applied between probe and surface.
- Electrons “tunnel” from probe to surface, resulting in weak electrical current.
- Smaller the distance between probe and surface, the greater the current.
- By scanning probe over surface