CEM 141 Test 2 Questions with 100% Complete
Solutions
Evidence that light is a wave
Light is a wave because when light goes through 2 slits a diffraction pattern occurs.
Reasoning that light is a wave
the waves from each slit meet "in phase" or "out of phase" when the waves meet in phase
constructive interference occurs and the wave intensity increases. this is seen by bright spots in
the patterns. when the waves meet out of phase destructive interference occurs and the waves
cancel each other out. Causing dark spots in the patterns.
diffraction gives rise to patterns of light and dark when waves pass through the double slit.
Evidence light is a particle
the photoelectric effect shows that there is threshold frequency below which no electron can be
emitted no matter how much intensity there is
Reasonings light is a particle
when you eject an electron from an atom, a minimum amount of energy is required. increase in
energy there is an increase in intensity if light was a wave. there is only a certain amount of
electrons that can be ejected, but eventually it runs out even if threshold is met. If photon doesn't
have enough energy to allow the electron to escape then nothing can happen.
, the energy of light must come in distinct packets and is not continuous so that one packet is
absorbed by one electron that is ejected from the atom.
Why does the photoelectric effect disprove that light is a wave
if light were a wave then electrons should continue to absorb the waves and overtime acclimate
the required energy to be ejected. however since this doesn't happen light must carry energy in
discrete molecules.
how many photons eject 1 electron?
1
What are different kinds of light and what order do they go in from most energy to least?
V I B G Y O R ( long wavelength, low energy, low frequency)
What is the atomic radius?
forces of attraction between electrons and protons are equal to the repulsion between electrons
When does atomic radius increase and decrease?
atomic radius increases as you go down the periodic table, but decreases as you go across
Why does the atomic radius decrease across a column?
across a row the number of protons increase but there isn't an added orbit for the electrons. So
the pull between protons and electrons are stronger because the electrons feel the positive charge
more and are more attracted
What is the effective nuclear charge?
Solutions
Evidence that light is a wave
Light is a wave because when light goes through 2 slits a diffraction pattern occurs.
Reasoning that light is a wave
the waves from each slit meet "in phase" or "out of phase" when the waves meet in phase
constructive interference occurs and the wave intensity increases. this is seen by bright spots in
the patterns. when the waves meet out of phase destructive interference occurs and the waves
cancel each other out. Causing dark spots in the patterns.
diffraction gives rise to patterns of light and dark when waves pass through the double slit.
Evidence light is a particle
the photoelectric effect shows that there is threshold frequency below which no electron can be
emitted no matter how much intensity there is
Reasonings light is a particle
when you eject an electron from an atom, a minimum amount of energy is required. increase in
energy there is an increase in intensity if light was a wave. there is only a certain amount of
electrons that can be ejected, but eventually it runs out even if threshold is met. If photon doesn't
have enough energy to allow the electron to escape then nothing can happen.
, the energy of light must come in distinct packets and is not continuous so that one packet is
absorbed by one electron that is ejected from the atom.
Why does the photoelectric effect disprove that light is a wave
if light were a wave then electrons should continue to absorb the waves and overtime acclimate
the required energy to be ejected. however since this doesn't happen light must carry energy in
discrete molecules.
how many photons eject 1 electron?
1
What are different kinds of light and what order do they go in from most energy to least?
V I B G Y O R ( long wavelength, low energy, low frequency)
What is the atomic radius?
forces of attraction between electrons and protons are equal to the repulsion between electrons
When does atomic radius increase and decrease?
atomic radius increases as you go down the periodic table, but decreases as you go across
Why does the atomic radius decrease across a column?
across a row the number of protons increase but there isn't an added orbit for the electrons. So
the pull between protons and electrons are stronger because the electrons feel the positive charge
more and are more attracted
What is the effective nuclear charge?
