quantum phenomona Flashcards
equation to find ek max of electron
hf - work function
define threshold frequency
minimum frequency of light required for electron to be emitted from surface of metal
define work function
minimum energy required to remove electron from surface of metal
state first conclusion about photoelectric effect
number of electrons emitted is proportional to intensity of radiation
state second conclusion about photoelectric effect
photoelectrons are emitted with varying kinetic energies, from zero to max value.
max kinetic energy increases with radiation frequency
state third conclusion about photoelectric effect
for a given metal, no electrons emitted if frequency of radiation below certain value = threshold frequency
state fourth conclusion about photoelectric effect
max kinetic energy unaffected by intensity of radiation, only frequency
define excitation
movement of an electron to a higher energy level
electron absorb discrete amount of photon energy
define de-excitation
movement of an electron to a lower energy level
electron emit discrete amount of energy as a photon
define ionisation
electron is removed/added to an atom
define electron collisions
when atoms are bombarded with free electrons and if one electron collides with an electron within the atom, some Ek is transferred. if enough, excites the electron
what phenomenon can be used to show light as a particle
the photoelectric effect
what is the photoelectric effect
when electrons on the surface of a metal absorb photons above a particular frequency to then be liberated
in the photoelectric effect, photons are absorbed in a ___ to ___ interaction
one to one interaction
what is an electron volt
the kinetic energy of an electron if accelerated through a potential difference of 1V
equation for threshold frequency
work function ÷ plank’s constant
phenomena to describe light as a wave
electron diffraction
the difference in energies between two energy levels is equal to…
the energy carried by the photon emitted after a transition
what vapour do fluorescent tubes contain
mercury vapour
why does the mercury vapour in a fluorescent tube need to have a high potential difference applied
to accelerate the free electrons to collide with the electrons in the mercury vapour and excite them to a higher energy level
photons emitted from de-excitation have a range of ___ and ___ that correspond to the different ___ of the electrons
energies
wavelengths
transitions
what coating does the fluorescent tube have
phosphorus coating
what does the phosphorus coating in fluorescent tubes do
the phosphorus coating absorbs the emitted photons, exciting its electrons to higher energy levels, which de-excite to emit photons
what does it mean for the wavelength and frequency of the photon emitted if an electron de-excites with a big energy difference
if the difference in energy between 2 energy levels is large then the photon emitted has a high frequency and short wavelength
what does it mean for the wavelength and frequency of the photon emitted if an electron de-excites with a small energy difference
if the difference in energy between 2 energy levels is small then the photon emitted has a low frequency and long wavelength
what does a line emission spectra look like
a series of bright lines against a black background
what does each line in a line emission spectra correspond to
a particular wavelength of light emitted
state the de broglie wavelength equation
λ = h / mv
describe electron diffraction
electrons are accelerated to high velocities in a vacuum, then passed through a graphite crystal.
the electrons diffract, producing a diffraction pattern
in electron diffraction, if the spread of lines in a diffraction pattern is increasing, what does it mean for the wavelength of the wave
it means a greater wavelength
in electron diffraction, if the spread of lines in a diffraction pattern is decreasing, what does it mean for the wavelength of the wave
it means a smaller wavelength
in electron diffraction, if there is a smaller accelerating voltage (slower electrons), what does it mean for the space in between the rings
larger spaced rings in the diffraction pattern
in electron diffraction if the electrons are sped up (higher accelerating voltage), what does it mean for the diffraction pattern shown
the gaps in between the rings are smaller
what is the condition for electrons to diffract during electron diffraction
the electron must interact with an object of about the same size as its de broglie wavelength
state the photoelectric equation
ekmax = hf - work function
