Topic 2 - Quantum Phenomena Flashcards
De Broglie hypothesis
Matter particles have a wave-like nature characterised by the de Broglie wavelength.
De Broglie wavelength
The wavelength of a matter particle = h/p where p is the momentum of the particle.
De excitation
Process in which an atom loses energy by photon emission, as a result of an electron inside moving from an outer energy shell to an inner energy shell.
Electron volt
Amount of energy equal to 1.6x10^-19J defined as the work done when an electron is moved through a pd of 1V.
Energy levels
The energy of an electron in an electron shell of an atom.
Excitation
Process in which an atom absorbs energy without becoming ionised as a result of an electron inside an atom moving from an inner energy shell to an outer energy shell.
Fluorescence
Glow of light from a substance exposed to ultraviolet radiation; the atoms de-excite in stages and emit visible photons in the process.
Ground state
Lowest energy state of an atom.
Ion
A charged atom.
Ionisation
Process of creating ions
Photoelectric effect
Emission of electrons from a metal surface when the surface is illuminated by light o frequency greater than a minimum value known as the threshold frequency.
Photon
Packet or ‘quantum’ of electromagnetic waves.
Stopping potential
The minimum potential that needs to be applied to a metal plate to attract all the photoelectrons emitted from its surface back to the surface.
Threshold frequency
Minimum frequency of light that can cause photoelectric effect.
Types of light spectra.
Continuous spectrum - continuous range of colour corresponding to a continuous range of wavelengths, line emission spectrum - characteristic coloured vertical lines, each corresponding to a certain wavelength, line absorption spectrum - dark vertical lines against a continuous range of colours, each line corresponding to a certain wavelength.
