Quiz quantum phenomena Ernest Rutherford Max Planck Albert
Quiz quantum phenomena Ernest Rutherford Max Planck Albert Einstein Niels Bohr Louis De Broglie
Concep. Test 37. 1 Which has more energy, a photon of: Photons 1) red light 2) yellow light 3) green light 4) blue light 5) all have the same energy 400 nm 500 nm 600 nm 700 nm
Concep. Test 37. 1 Which has more energy, a photon of: Photons 1) red light 2) yellow light 3) green light E = hf 400 nm 4) blue light 5) all have the same energy 500 nm 600 nm 700 nm The photon with the highest frequency has the most energy because E = hf = hc/l (recall that c = f l). So a higher frequency corresponds to a lower wavelength The highest energy of the above choices is blue
Photoelectric Effect I If the cutoff frequency for light in 1) metal A the photoelectric effect for metal 2) metal B B is greater than that of metal A, which metal has a greater work function? 3) same for both 4) W 0 must be zero for one of the metals KE Concep. Test 37. 2 a f 0 f
Photoelectric Effect I If the cutoff frequency for light in 1) metal A the photoelectric effect for metal 2) metal B B is greater than that of metal A, which metal has a greater work function? 3) same for both 4) W 0 must be zero for one of the metals A greater cutoff frequency means a higher energy is needed to knock out the electron. But this implies that the work function is greater, greater since the work function is defined as the minimum amount of energy needed to eject an electron. KE Concep. Test 37. 2 a f 0 Follow-up: What would you expect to happen to the work function of a metal if the metal was heated up? f
Concep. Test 37. 2 b Photoelectric Effect II A metal surface with a work 1) emitted electrons are more energetic function of W 0 = hc/550 nm 2) emitted electrons are less energetic is struck with blue light and 3) more electrons are emitted in a given electrons are released. If the time interval blue light is replaced by red 4) fewer electrons are emitted in a given light of the same intensity, what is the result? time interval 5) no electrons are emitted
Concep. Test 37. 2 b Photoelectric Effect II A metal surface with a work 1) emitted electrons are more energetic function of W 0 = hc/550 nm 2) emitted electrons are less energetic is struck with blue light and 3) more electrons are emitted in a given time interval electrons are released. If the blue light is replaced by red light of the same intensity, 4) fewer electrons are emitted in a given time interval what is the result? 5) no electrons are emitted Red light has a wavelength of about 700 nm. nm The cutoff wavelength is 550 nm (yellow light), light which is the maximum wavelength to knock out electrons. Thus, no electrons are knocked out energy high 400 nm 500 nm 600 nm E = hc / l low 700 nm
Concep. Test 37. 2 c Photoelectric Effect III A metal surface is struck with 1) more electrons are emitted in a given time interval light of l = 400 nm, releasing 2) fewer electrons are emitted in a given a stream of electrons. If the time interval 400 nm light is replaced by l 3) emitted electrons are more energetic = 370 nm light of the same 4) emitted electrons are less energetic intensity, what is the result? 5) none of the above
Concep. Test 37. 2 c Photoelectric Effect III A metal surface is struck with 1) more electrons are emitted in a given time interval light of l = 400 nm, releasing 2) fewer electrons are emitted in a given a stream of electrons. If the time interval 400 nm light is replaced by 3) emitted electrons are more energetic l = 370 nm light of the same 4) emitted electrons are less energetic intensity, what is the result? 5) none of the above A reduced wavelength means a higher frequency, frequency which in turn means a higher energy So the emitted electrons will be more energetic, energetic since they are now being hit with higher energy photons. Remember that c = f l and that E = hf.
Concep. Test 37. 2 d Photoelectric Effect IV A metal surface is struck with 1) more electrons are emitted in a given time interval light of l = 400 nm, releasing a stream of electrons. If the 2) fewer electrons are emitted in a given time interval light intensity is increased 3) emitted electrons are more energetic (without changing l), what is 4) emitted electrons are less energetic the result? 5) none of the above
Concep. Test 37. 2 d Photoelectric Effect IV A metal surface is struck with 1) more electrons are emitted in a given time interval light of l = 400 nm, releasing a 2) fewer electrons are emitted in a given stream of electrons. If the time interval light intensity is increased 3) emitted electrons are more energetic (without changing l), what is the result? 4) emitted electrons are less energetic 5) none of the above A higher intensity means more photons, photons which in turn means more electrons. On average, each photon knocks out one electron.
Concep. Test 37. 2 e Photoelectric Effect V A photocell is illuminated with light with a frequency above the cutoff frequency. The magnitude 1) wavelength of the light 2) intensity of the light 3) frequency of the light of the current produced depends 4) all of the above on: 5) none of the above
Concep. Test 37. 2 e Photoelectric Effect V A photocell is illuminated with light with a frequency above the cutoff frequency. The magnitude 1) wavelength of the light 2) intensity of the light 3) frequency of the light of the current produced depends 4) all of the above on: 5) none of the above Each photon can knock out only one electron. So to increase the current, we would have to knock out more electrons, electrons which means we need more photons, photons which means we need a greater intensity! intensity Changing the frequency or wavelength will change the energy of each electron, but we are interested in the number of electrons in this case.
Concep. Test 37. 3 a Wave–Particle Duality I The speed of proton A is 1) proton A larger than the speed of 2) proton B. Which one has the 3) both the same longer wavelength? 4) neither has a wavelength
Concep. Test 37. 3 a Wave–Particle Duality I The speed of proton A is 1) proton A larger than the speed of 2) proton B. Which one has the 3) both the same longer wavelength? 4) neither has a wavelength Remember that so the proton with the smaller velocity will have the longer wavelength.
Concep. Test 37. 3 b An electron and a proton have the same speed. Which has the longer wavelength? Wave–Particle Duality II 1) electron 2) proton 3) both the same 4) neither has a wavelength
Concep. Test 37. 3 b An electron and a proton have the same speed. Which has the longer wavelength? Remember that Wave–Particle Duality II 1) electron 2) proton 3) both the same 4) neither has a wavelength and the particles both have the same velocity, so the particle with the smaller mass will have the longer wavelength.
Concep. Test 37. 3 d Wave–Particle Duality IV An electron and a proton 1) electron have the same momentum. 2) proton Which has the longer 3) both the same wavelength? 4) neither has a wavelength
Concep. Test 37. 3 d Wave–Particle Duality IV An electron and a proton 1) electron have the same momentum. 2) proton Which has the longer 3) both the same wavelength? 4) neither has a wavelength Remember that and p = mv, mv so if the particles have the same momentum, they will also have the same wavelength.
Concep. Test 37. 4 Ionization 1) 0 e. V How much energy does it 2) 13. 6 e. V take to ionize a hydrogen 3) 41. 2 e. V atom in its ground state? 4) 54. 4 e. V 5) 108. 8 e. V
Concep. Test 37. 4 Ionization 1) 0 e. V How much energy does it 2) 13. 6 e. V take to ionize a hydrogen 3) 41. 2 e. V atom in its ground state? 4) 54. 4 e. V 5) 108. 8 e. V The energy of the ground state is the energy that binds the electron to the nucleus. Thus, an amount equal to this binding energy must be supplied in order to kick the electron out of the atom. Follow-up: How much energy does it take to change a He+ ion into a He++ ion? Keep in mind that Z = 2 for helium.
Concep. Test 37. 5 a For the possible transitions shown, for which transition will the electron gain the most energy? Atomic Transitions I 1) 2 5 2) 5 3 3) 8 5 4) 4 7 5) 15 7 n=5 n=4 n=3 n=2 n=1
Concep. Test 37. 5 a Atomic Transitions I For the possible transitions shown, for which transition will the electron gain the most energy? The electron must go to a higher orbit (higher n) in order for the electron to gain energy. Because of the 1/n 2 dependence: E 2 – E 5 > E 4 – E 7 1) 2 5 2) 5 3 3) 8 5 4) 4 7 5) 15 7 n=5 n=4 n=3 n=2 n=1 Follow-up: Which transition will emit the shortest wavelength photon?
Concep. Test 37. 7 b Energy Levels II The emission spectrum for the atoms of a gas is shown. Which of the energy level diagrams below corresponds to this spectrum? (1) (2) (3) (4)
Concep. Test 37. 7 b Energy Levels II The emission spectrum for the atoms of a gas is shown. Which of the energy level diagrams below corresponds to this spectrum? (1) (2) (3) (4) Each line in the spectrum corresponds to a transition between energy levels! Since there are 6 transitions shown, there must be 4 levels The 2 transitions between the closely spaced levels have less energy, while the other 4 have larger energies
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