quantum phenomona

Question 1

equation to find ek max of electron

Answer 1

hf - work function

Question 2

define threshold frequency

Answer 2

minimum frequency of light required for electron to be emitted from surface of metal

Question 3

define work function

Answer 3

minimum energy required to remove electron from surface of metal

Question 4

state first conclusion about photoelectric effect

Answer 4

number of electrons emitted is proportional to intensity of radiation

Question 5

state second conclusion about photoelectric effect

Answer 5

photoelectrons are emitted with varying kinetic energies, from zero to max value.
max kinetic energy increases with radiation frequency

Question 6

state third conclusion about photoelectric effect

Answer 6

for a given metal, no electrons emitted if frequency of radiation below certain value = threshold frequency

Question 7

state fourth conclusion about photoelectric effect

Answer 7

max kinetic energy unaffected by intensity of radiation, only frequency

Question 8

define excitation

Answer 8

movement of an electron to a higher energy level
electron absorb discrete amount of photon energy

Question 9

define de-excitation

Answer 9

movement of an electron to a lower energy level
electron emit discrete amount of energy as a photon

Question 10

define ionisation

Answer 10

electron is removed/added to an atom

Question 11

define electron collisions

Answer 11

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

Question 12

what phenomenon can be used to show light as a particle

Answer 12

the photoelectric effect

Question 13

what is the photoelectric effect

Answer 13

when electrons on the surface of a metal absorb photons above a particular frequency to then be liberated

Question 14

in the photoelectric effect, photons are absorbed in a ___ to ___ interaction

Answer 14

one to one interaction

Question 15

what is an electron volt

Answer 15

the kinetic energy of an electron if accelerated through a potential difference of 1V

Question 16

equation for threshold frequency

Answer 16

work function ÷ plank’s constant

Question 17

phenomena to describe light as a wave

Answer 17

electron diffraction

Question 18

the difference in energies between two energy levels is equal to…

Answer 18

the energy carried by the photon emitted after a transition

Question 19

what vapour do fluorescent tubes contain

Answer 19

mercury vapour

Question 20

why does the mercury vapour in a fluorescent tube need to have a high potential difference applied

Answer 20

to accelerate the free electrons to collide with the electrons in the mercury vapour and excite them to a higher energy level

Question 21

photons emitted from de-excitation have a range of ___ and ___ that correspond to the different ___ of the electrons

Answer 21

energies
wavelengths
transitions

Question 22

what coating does the fluorescent tube have

Answer 22

phosphorus coating

Question 23

what does the phosphorus coating in fluorescent tubes do

Answer 23

the phosphorus coating absorbs the emitted photons, exciting its electrons to higher energy levels, which de-excite to emit photons

Question 24

what does it mean for the wavelength and frequency of the photon emitted if an electron de-excites with a big energy difference

Answer 24

if the difference in energy between 2 energy levels is large then the photon emitted has a high frequency and short wavelength

Question 25

what does it mean for the wavelength and frequency of the photon emitted if an electron de-excites with a small energy difference

Answer 25

if the difference in energy between 2 energy levels is small then the photon emitted has a low frequency and long wavelength

Question 26

what does a line emission spectra look like

Answer 26

a series of bright lines against a black background

Question 27

what does each line in a line emission spectra correspond to

Answer 27

a particular wavelength of light emitted

Question 28

state the de broglie wavelength equation

Answer 28

λ = h / mv

Question 29

describe electron diffraction

Answer 29

electrons are accelerated to high velocities in a vacuum, then passed through a graphite crystal.
the electrons diffract, producing a diffraction pattern

Question 30

in electron diffraction, if the spread of lines in a diffraction pattern is increasing, what does it mean for the wavelength of the wave

Answer 30

it means a greater wavelength

Question 31

in electron diffraction, if the spread of lines in a diffraction pattern is decreasing, what does it mean for the wavelength of the wave

Answer 31

it means a smaller wavelength

Question 32

in electron diffraction, if there is a smaller accelerating voltage (slower electrons), what does it mean for the space in between the rings

Answer 32

larger spaced rings in the diffraction pattern

Question 33

in electron diffraction if the electrons are sped up (higher accelerating voltage), what does it mean for the diffraction pattern shown

Answer 33

the gaps in between the rings are smaller

Question 34

what is the condition for electrons to diffract during electron diffraction

Answer 34

the electron must interact with an object of about the same size as its de broglie wavelength

Question 35

state the photoelectric equation

Answer 35

ekmax = hf - work function