QUANTUM Flashcards
what is the eV
is the energy gained by an electron, accelerated by a pd of 1v
how do you convert from V to eV ?
multiply by 1.6x10^-19
what is the relationship between the frequency of a particle and the frequency of the wave
E=hf
what is planck’s constant
6.63x10^-34
what is the threshold voltage?
a value below which a no current will flow through the diode
what is the wavelength of red light?
700 nanometers
what is the wavelength of blue light?
450 nanometers
what is the wavelength of green light?
550 nanometers
what will the gradient be on a V over 1/λ graph?
Vλ or hc/e
since
e=hf=hc/λ
e=eV
eV=hc/λ
vλ =hc/e
what is the photoelectric effect
when electromagnetic radiation of a particular frequency is shone on the surface of a meal, electrons are emitted from its surface.
what is the work function
Is the minimum energy required to release an electron from the surface, overcoming the electrostatic attraction between the electron and the positive metal ions.
what is the energy of a photon directly proportional to ?
The frequency.
E=hf
what is the work function
the minimum energy required to release a delocalised electron from the surface of the metal
what happens when the energy of the photon is equal to the work function
we get the threshold frequency
what is the threshold frequency
minimum frequency required to release the delocalised electron from the surface
what happens if the incident photon has more than the threshold frequency
there will be energy left over, this will be the kinetic energy of the electron.
if an electron is emitted in an electric field, what direction will in go in relation to the field lines
opposite, it will take a parabolic motion, forming a current as long as it reachers the other plate.
how do you calculate the work done moving an electron across a potential difference?
W=eV, charge of electron, by the potential difference.
what is stopping potential?
where the Ek, is equal to the charge x the pd, we call this pd the stopping pd. any pd greater will stop the current.
how do you calculate stopping potential
hf=Ø+Vs
what are energy levels
these are the levels in which electrons can orbit a nucleus. they go from 1 to infinity hypothetically
what causes electrons to move energy levels
photons, heat…
what happens to the energy stored in an electron when it moves up an energy level
it loses energy as a photon of radiation.
