AS Physics - Electron Diffraction

(for AQA AS Physics)

• Electron diffraction shows the wave nature of electrons (how electrons can behave like waves)
• Diffraction patterns are observed when accelerated electrons in a vacuum tube interact with the spaces in a graphite crystal - this confirms electrons show wavelike properties
• According to the wave theory - the spread of the lines in the diffraction pattern increases if the wavelength of the wave is greater
• In experiments: a smaller accelerating voltage (the electrons are slower which gives widely spaced rings
• Increase in the electron speed - the diffraction pattern circles squash together towards the middle. (fits with the de Broglie equation  - if velocity is higher the wavelength is shorter and the spread of the lines smaller)

Wavelength for electrons accelerated in a vacuum tube is about the same size as electromagnetic waves in the X-ray part of the spectrum