AS2 2.6 Wave-particle duality

Question 1

What is explained by a wave model?

Answer 1

• Interference
• Diffraction
• Polarisation
• Electron Diffraction

Question 2

What can be explained by a particle model?

Answer 2

• Photoelectric effect
• Emission spectra
• Fluorescence

Question 3

What can be explained by both the particle and wave models?

Answer 3

• Reflection
• Refraction

Question 4

What cant the wave theory of light explain?

Answer 4

1. The existence of a threshold frequency
2. Intensity of radiation having no effect below f0
3. Increased KE as f increases above f0
4. No time delay for electrons to be emitted

Question 5

Electron Diffraction Experiment

Answer 5

1. Evacuated (vacuum) tube
2. Electrons released via thermionic emission
3. Accelerated inside electric field
4. Pass through a metal foil/carbon film/crystal structure
5. Electrons diffracted, interference pattern set up on screen
6. Screen made from fluorescent material, light where there is constructive inteference

Question 6

De Broglie Wavelength Equation

Answer 6

Lambda = h / p
h is plancks constant
p is momentum (mxv)

Question 7

What is the De Broglie Wavelength

Answer 7

It is the wavelength of a matter wave associated with a moving mass