Wave-particle duality Flashcards
What is the evidence for light as a particle?
1) the photo electric effect- if a photon of light is a discrete bundle of energy, then it can interact with an electron in a one-to-one way and all the energy in the photon if given to one electron.
What is the evidence for light as a wave?
1) Reflection - if a ray of light approaches a shiny surface/ mirror it will be reflected.
2) Refraction - When a wave enters a medium with a different density it changes direction. governed by Snell’s Law.
3) Diffraction- When light passes through a narrow slit, the emerging light spreads out.
What experiment can be used to show the wave behaviour of electrons?
The double slit experiment
What evidence is there for the wave behaviour of light?
Light diffracts, reflects and refracts
What evidence is there for the particle behaviour of light?
The photoelectric effect
What shows particles behaving as particles?
They are deflected in a magnetic field.
What is the formula for the de Broglie wavelength and what does it show particles acting as?
λ= h/mv
λ = wavelength (m) h= Planck's Constant m= mass (kg) V= Velocity (m/s)
It gives an associated wavelength to all particles, showing the nature of particles acting as waves.
How can you work out momentum of a particle?
momentum = it’s mass in kilograms (kg) by it’s velocity in metres per secons (m s-1)
what unit is momentum measured in?
kg m s-1
How does electron diffraction support wave theory?
and how does this fit with the de Broglie equation?
According to wave theory the spread of lines in the diffraction pattern increases if the wavelength is greater. In electron diffraction experiments, a smaller accelerating voltage (slower electrons) gives widely spaced rings.
This fits in with the de Broglie equation-if the velocity is higher, the wavelength is shorter and the spread of lines is smaller.
How does an electron microscope resolve finer detail than a light microscope?
A shorter wavelength gives less diffraction effects and diffraction effects blur detail.
What is has the same wavelength as EM radio waves?
The wavelength for electrons accelerated in a vacuum
State what is meant by the wave particle duality of electrons?
electrons can have wavelike properties and particle properties
What kind of experiment would confirm that electrons have a wave-like nature
diffraction
Why is it easier to demonstrate the wave properties of electrons than to demonstrate wave properties of protons?
easier to obtain electrons OR easier to get the same wavelength the same size as the scattering objects.
