Module 4 - Quantum (Wave-Particle Duality) Flashcards
Describe what is meant by wave-particle duality
The idea that EM Radiation can display both wave and particle properties and that matter under circumstances can display both wave and particle properties
What are de Broglie waves
any matter moving with mass that displays wave like properties
What are properties that evidence EM radiation being a wave
Polarisation
Diffraction
Reflection
Refraction
What are properties that evidence EM radiation being a particle
- The photoelectric effect
What are 2 things de Broglie discovered about matter
- Anything with mass that moves, has wave-like properties
- Anything that has momentum has a corresponding wavelength
What is de Broglie’s base equation
λ = h/p
- λ: de Broglie wavelength
- h: plancks constant
- p: momentum
What is de Broglie’s broken down equation
λ= h/mv
- λ: de Broglie wavelength
- h: plancks constant
- m: relativistic mass
- v: velocity
What is de Broglie’s equation linked to the Eₖ of the matter
λ= h/√(2Eₖm)
- λ: de Broglie wavelength
- h: plancks constant
- m: relativistic mass
- Eₖ: kinetic energyD
Derive the de Broglie’s equation linked to the Eₖ of the matter
λ= h/mv , and Eₖ = 0.5mv²
- 2Eₖ = mv²
- 2mEₖ =m²v²
- mv = √(2Eₖm)
λ= h/√(2Eₖm)
What is meant by relativistic mass
- The idea that as the velocity of the object tends towards the speed of light, its mass tends to increase
What are the relationships between de Broglie wavelength and three other quantities
λ ∝ 1/p
λ ∝ 1/v (for a constant mass)
λ ∝ 1/√Eₖ (for a constant mass)
Describe the relationship between de Broglie wavelength and momentum
The associated wavelength can change and is dependent on the momentum of the matter, the greater the momentum the smaller the wavelength
What are the components of the Electron Diffraction experiment
- Cathode Filament
- Vacuum
- Anode with hole to concentrate electrons
- Polycrystalline graphite
- Screen
Describe the material properties of polycrystalline graphite that make it suitable for electron diffraction
- Thin, lattice of carbon, that has atomic spacing with lengths comparable to the wavelength of the fired electrons
Describe how the concentrated beam of electrons create an interference pattern on the screen
- As the electrons approach the spaces between atoms, the electrons diffract
- This diffraction generates 2 coherent waves as the electrons act as a wave that interfere with themselves
Why dont larger objects show wave like properties
Larger objects have wave properties that are too hard to observe
What is the rest mass of an electron
9.11 x 10⁻³¹
