quantam phenomena Flashcards
what is the photoelectric effect
emission of electrons from a metal’s surface
when surface is illuminated by light of frequency greater than threshold frequency
what is the threshold frequency
lowest frequency of light that when shone on a metal will cause the release of electrons from it
what does increasing radiation frequency do to electron energy
increasing frequency of radiation causes increase in electron kinetic energy
what does increasing intensity radiation do emitted electrons
no effect on energy
increases the number of photo electrons emitted per second
what is ionisation
the process of creating ions
what are ions
they are charged atoms
what is the ground state
The lowest energy state of an atom
what is the excited state
an atom not in it’s ground state
what are energy levels
the energy of an electron in an electron shell of an atom
or the allowed energies of a nucleus
what is the energy transfer of photons to an electron like
the photons transfer all energy to one specific electron in a one on one particle like interaction
what is an electron volt
kinetic energy carried by an electron after it has been accelerated from rest though a potential difference of 1 volt
how do excited electrons move down energy levels
they move down to lower energy levels by emitting a photon
what is the energy of the photon emitted when an electron de excites
it is equal to the difference in energies between the two levels
how else can electrons move up energy levels
if they absorb a photon with exact difference in energies between the two levels
what is excitation
movement of an electron to a higher energy level
what is stopping potential
the potential difference needed to stop the fastest moving photoelectrons
in the photoelectric effect
what is a line emission spectrum and how is it formed
a series of bright lines against a black background each line corresponding to a different wavelength of light
made by splitting the light from a flourscenet tube
how is a line absorption spectrum formed
when light with a continuous spectrum of energy passes through a cool gas
electrons are excited by absorbing photons of the correct energy the wavelengths are the missing from the continuous spectrum
black lines are the absorbed wavelengths
