Quantum phenomena - 3 Flashcards
describe the photoelectric effect
phenomenon in which electrically charged particles are released from or within a material when it absorbs electromagnetic radiation (photons).
when does the photoelectric effect not happen
when the incident photons are below the threshold frequency - below the work function
what is the threshold frequency
The threshold frequency is the minimum frequency of a photon required for photoemission
describe the photoelectric effect experiment
UV light is shon onto a zinc plate which is negitivly charged and the gold leaf is suspended. As the UV light is shon electrons leave the zinc plate allowing the leaf to fall
what does h show in the formula sheet
planks constant
what does c represent in the formula sheet
speed of light
as energy of a photon increases what else increases
its frequency
why is an exact amount of photon energy required to excite a hydrogen atom?
all photon energy is absorbed which must match that of the energy difference in the energy levels
why is a hydrogen atom colliding with a free electron required to have a minimum energy?
electron collision transfers ke so any extra just transfers to ke
what intensity of em waves emitted electrons from a metal
low intensity, high frequency
what happens in electron capture?
proton turns to a neutron and a neutrino is produced
why does the kinetic energy of emitted electrons have a maximum value
can only have the same energy as the incident photons, energy required to remove the electron varies depending on the energy levels
what’s the unit for the work function
joule
if there is no time delay in the emission of electrons from a metal what does this show?
that light has a particle like nature and travels in discrete energy packets
state what is meant by a work function
min energy to remove an electron from the surface of a metal
