PHYS131 - Ch. 27, 28, 29

1.78×10^14 Hz

A Hydrogen atom is excited to the n = 11 level. Its decay to the n = 4 level is detected in a photographic plate. What is the frequency of the light photographed? 1680 nm 1.78×10^14 Hz 1680 Hz 1.46×10^−9 km

1640 nm

A Hydrogen atom is excited to the n = 12 level. Its decay to the n = 4 level is detected in a photographic plate. What is the wavelength of the detected emission? 875 nm 2760 nm 1640 nm 867 nm

c.) has a smaller wavelength than a red photon and travels with the same speed.

A blue photon a.) has a smaller wavelength than a red photon and travels with a greater speed. b.) has a longer wavelength than a red photon and travels with a greater speed. c.) has a smaller wavelength than a red photon and travels with the same speed. d.) has a longer wavelength than a red photon and travels with the same speed.

ρ.

A certain atomic nucleus containing 50 nucleons has a density ρ. If another nucleus contains 150 nucleons, its density will be closest to A certain atomic nucleus containing nucleons has a density . If another nucleus contains nucleons, its density will be closest to 3ρ. 32/3ρ=2.08ρ. 31/3ρ=1.44ρ. 3√ρ=1.73ρ. ρ.

2.1×10^18

A laser emits a pulse of light that lasts 10 ns. The light has a wavelength of 690 nm, and each pulse has an energy of 600 mJ. How many photons are emitted in each pulse? 2.1×10^18 2.7×10^27 3.9×10^43 3.3×10^37

2 × 10-5 eV

A laser produces a beam of 4000 nm light. A shutter allows a pulse of light, 30 ps in duration, to pass. The uncertainty in the energy of a photon in the pulse is closest to: 2 × 10-5 eV 2 × 10-4 eV 2 × 10-6 eV 2 × 10-3 eV 2 × 10-2 eV

3.9×10^18

A laser pulse of duration 25 ms has a total energy of 2.1 J. If the wavelength of this radiation is 372 nm, how many photons are emitted in one pulse? 3.9×10^18 3.1×10^17 4.7×10^19 1.6×10^17 9.8×10^19

3^(1/3) R=1.44R.

A nucleus containing 60 nucleons has a radius R . The radius of a nucleus containing 180 nucleons would be closest to 3^(2/3) R=2.08R. √3 R=1.73R. 3R. 3^(1/3) R=1.44R.

2.7×10−19 J

A photocathode has a work function of 2 eV. The photocathode is illuminated with monochromatic radiation whose photon energy is 3.7 eV. The maximum kinetic energy of the photoelectrons produced is closest to: 3.2×10−19 J 2.7×10−19 J 4.1×10−19 J 5.0×10−19 J 5.9×10−19 J

290 nm

A photocathode has a work function of 2.2 eV. The photocathode is illuminated with monochromatic radiation whose photon energy is 4.3 eV. The wavelength of the illuminating radiation is closest to: 290 nm 270 nm 310 nm 240 nm 340 nm

6.8×1014 Hz

A photocathode has a work function of 2.8 eV. The photocathode is illuminated with monochromatic radiation whose photon energy is 4.2 eV. The threshold frequency for photoelectron production is closest to: 9×1014 Hz 1.0×1015 Hz 6.8×1014 Hz 3.4×1014 Hz 7.8×1014 Hz

white light illumination is closest to: 1.2 V

A photocathode whose work function is 2.2 eV is illuminated with white light that has a continuous wavelength band from 370 nm to 700 nm. The stopping potential for this white light illumination is closest to: 1.2 V 1.0 V 1.5 V 1.3 V 1.4 V

560 to 700

A photocathode whose work function is 2.2 eV is illuminated with white light that has a continuous wavelength band from 400 nm to 700 nm. The range of the wavelength band in this white light illumination for which photoelectrons are not produced, in nm, is closest to: 560 to 700 400 to 640 640 to 700 560 to 640 400 to 560

1/3E.

A photon of wavelength λ has energy E. If its wavelength were triple, its energy would be If its wavelength were triple, its energy would be 9E. 3E. 1/3E. 1/9E.

14.4 eV

A proton and an electron are 1.00 Å apart. (Å is the Ångstrom unit, which is 10-10 m.) The potential energy of this pair of charges is closest to 14.4 eV 14.4 J 1.44 eV 144 eV 14.4 keV

280 keV

A proton has a speed of 8.9 x 104 m/s. The energy of a photon that has the same de Broglie wavelength as the proton is closest to: 190 keV 370 keV 280 keV 550 keV 460 keV

Z+1

A radioactive nuclide of atomic number Z emits an electron, then the daughter nuclide emits a gamma ray. What is the atomic number of the resulting nuclide after both processes? Z+1 Z-1 Z-2 Z-3

c.) Attractive nuclear forces in the nucleus counteract the effect of the Coulomb forces.

A stable nucleus contains many protons very close to each other, all positively charged. Why do the protons not fly apart due to mutual Coulomb repulsion? a.) The neutrons in the nucleus shield the protons from each other. b.) The Coulomb force does not operate within nuclei. c.) Attractive nuclear forces in the nucleus counteract the effect of the Coulomb forces. d.) There are an equal number of electrons in the nucleus which neutralize the protons.

A. β− particle

After a particle was emitted from the nucleus of an atom, it was found that the atomic number of the atom had increased . The emitted particle could have been (there may be more than one correct choice) A. β− particle . B. an alpha particle. C. a positron (β+). D. a gamma ray.

2900 m/s

An electron has the same de Broglie wavelength as a 250 nm photon. The speed of the electron is closest to: 2900 m/s 2600 m/s 3200 m/s 840 m/s 2300 m/s

4300 m/s

An electron has the same de Broglie wavelength as a 7.3 eV photon. The speed of the electron is closest to: 4300 m/s 3100 m/s 3700 m/s 3400 m/s 4000 m/s

110 m/s

An electron's de Broglie wavelength is 6.4 μm. What is its speed? 9.4×104 m/s 3.1×106 m/s 630 m/s 110 m/s

N0/4.

Atom A has twice as long a half-life as atom B. If both of them start out with an amount N0, then in the time that A has been reduced to N0/2, B has been reduced to N0/2. N0/8. N0/16. N0/4.

28.30 A.) What is the minimum potential difference between the filament and the target of an x-ray tube if the tube is to accelerate electrons to produce x rays with a wavelength of 0.165 nm ? B.) What is the shortest wavelength produced in an x-ray tube operated at 29.6 kV ? C.) Would the answers to parts (A) and (B) be different if the tube accelerated protons instead of electrons? Why or why not?

C.) The answers would be the same; the charges of the electron and the proton have the same magnitude therefore the answers will be the same.

C: If an electron makes a transition from the n=3 to the n=1 shell, it will give up 73.2 eV of energy.

Consider a hypothetical single-electron Bohr atom for which an electron in the n=1 shell has a total energy of -82.0 eV while one in the n=3 shell has a total energy of -8.80 eV . Which statements about this atom are correct? (There may be more than one correct choice.) A: The energy needed to ionize the atom is 90.8 eV . B: It takes 90.8 eV to move an electron from the n=1 to the n=3 shell. C: If an electron makes a transition from the n=3 to the n=1 shell, it will give up 73.2 eV of energy. D: If an electron makes a transition from the n=3 to the n=1 shell, it must absorb 73.2 eV of energy.

λ/ √3.

Electron A has a de Broglie wavelength λ. If electron B has triply the kinetic energy (but a speed much less than that of light) of electron A, the de Broglie wavelength of electron B is 3λ. λ √3. λ/ √3. λ/3.

increases.

Electrons are accelerated from rest through a potential difference V. As V is decreased, the de Broglie wavelength of these electrons increases. decreases. does not change.

3.083555 eV

Find the energy (in eV) of an optical photon of frequency 7.45 × 1014 Hz. 3.083555 eV 2.2509952 eV 3.7927727 eV 1.8809686 eV

0.2304922 eV

Find the energy of the photon emitted when an electron drops from the n = 17 state to the n = 7 state in a hydrogen atom. 0.28581033 eV 0.24893157 eV 0.2304922 eV 0.26737095 eV

424.89726 nm

Find the wavelength (in nm) of a 2.92 eV photon. 361.16267 nm 467.38699 nm 505.62774 nm 424.89726 nm

d.) Isotopes of an element have nuclei with the same number of protons, but a different number of neutrons.

How do the nuclei of different isotopes of an element vary? a.) Isotopes of an element have nuclei with a different number of protons, but the same number of neutrons. b.) Isotopes of an element have nuclei with a different number of protons, but the same number of electrons. c.) Isotopes of an element have nuclei with the same number of protons and the same number of neutrons. d.) Isotopes of an element have nuclei with the same number of protons, but a different number of neutrons.

a.) The atomic mass number is determined only by the number of nucleons in the nucleus.

How is an atom's atomic mass number determined? a.) The atomic mass number is determined only by the number of nucleons in the nucleus. b.) The atomic mass number is determined only by the number of alpha particles emitted. c.) The atomic mass number is determined only by the number of beta particles emitted. d.) The atomic mass number is determined only by the number of electrons in the atom. e.) The atomic mass number is determined only by the number of protons in the nucleus. g.) The atomic mass number is determined only by the number of neutrons in the nucleus.

R/16.0.

If the Bohr radius of the n = 4.00 state of a hydrogen atom is R, then the radius of the ground state is 16.0 R. 4.00 R. R/4.00. R/16.0.

91.0 MeV .

If the binding energy per nucleon for hypothetical element 13/7 X is 7.00 MeV/nucleon , the total binding energy of its nucleus is 7.00 MeV . 42.0 MeV . 49.0 MeV . 91.0 MeV . 140 MeV .

81.0 E.

If the energy of the n = 9.00 state of a Bohr-model hydrogen atom is E, the energy of the ground state is 81.0 E. 9.00 E. E/ 9.00. E/ 81.0

a.) higher than that of the carbon nucleus.

In massive stars, three helium atoms fuse together, forming a carbon nucleus. This reaction heats the core of the star. The net mass of the three helium nuclei must therefore be a.) higher than that of the carbon nucleus. b.)the same as that of the carbon nucleus (mass is always conserved). c.) less than that of the carbon nucleus.

a.) the number of photons emitted by light every second.

Increasing the brightness of a beam of light without changing its color will increase a.) the number of photons emitted by light every second. b.) the speed of the photons. c.) the average energy of each photon. d.) Two of the above statements are true.

13.8 eV

Light excites atomic hydrogen from its lowest level to the n = 10 level. What is the energy of the light? 32.3 eV 92.1 eV 61.6 eV 13.8 eV

B: the maximum speed of the emitted electrons decreases.

Light falling on a metal surface causes electrons to be emitted from the metal by the photoelectric effect. As we decrease the frequency of this light, but do not vary anything else (there may be more than one correct answer), A: the number of electrons emitted from the metal increases. B: the maximum speed of the emitted electrons decreases. C: the maximum speed of the emitted electrons does not change. D: the work function of the metal increases.

greater than 2K.

Light of frequency f falls on a metal surface and ejects electrons of maximum kinetic energy K by the photoelectric effect. If the frequency of this light is doubled, the maximum kinetic energy of the emitted electrons will be K/2. K. 2K. greater than 2K.

b.) Too young.

Modern nuclear bomb tests have created an extra high level of 14C in our atmosphere. When future archaeologists date samples from this era, without knowing of this testing, will their dates be too young? Too old? Correct? If correct, why? A.) Too old. b.) Too young. c.) Correct, since 14C from bomb tests is different from that produced naturally. d.) Correct, because modern biological materials do not gather 14C from bomb tests.

a.) Greater rate; same maximum energy.

Monochromatic light is incident on a metal surface and electrons are ejected. If the intensity of the light is increased, what will happen to the ejection rate and maximum energy of the electrons? a.) Greater rate; same maximum energy. b.) Same rate; greater maximum energy. c.) Greater rate; greater maximum energy. d.) Same rate; same maximum energy.

It will remain unchanged.

Monochromatic light is incident on a metal surface. The ejected electrons give rise to a current in the circuit shown in the figure The maximum energy of the ejected electrons is determined by applying a reverse ('stopping') potential, sufficient to reduce the current in the ammeter to zero. If the intensity of the incident light is increased, how will the required stopping potential change? If the intensity of the incident light is increased, how will the required stopping potential change? It will increase. It will decrease. It will remain unchanged.

a.) number of protons.

Nuclei that are all isotopes of an element all have the same a.) number of protons. b.) number of neutrons. c.) number of nucleons. d.) mass.

20

One of the emission lines described by the original version of Balmer's formula has wavelength 368 nm. What is the value of n in Balmer's formula that gives this emission line? 20 21 22 23

Both λ/2 and λ/3

Part of the energy level diagram of a certain atom is shown in the figure The energy spacing between levels 1 and 2 is twice that between 2 and 3. If an electron makes a transition from level 3 to level 2, the radiation of wavelength λ is emitted. What possible radiation wavelengths might be produced by other transitions between the three energy levels? Both λ/2 and λ/3 Only λ/2 Both 2λ and 3λ Only 2λ

λ/2.

Proton A has a de Broglie wavelength λ. If proton B has twice the speed (which is much less than the speed of light) of proton A, the de Broglie wavelength of proton B is 2λ. λ √2. λ / √2. λ/2.

5.92 × 10-6 eV

Radioastronomers often study the radiation emitted by a hydrogen atom from a transition between the two hyperfine levels associated with the ground state. This radiation has a wavelength of 21 cm. What is the energy difference between the hyperfine levels? 4.73 × 10-25 J 5.92 × 10-6 eV 5.92 × 10-25 J 1.66 × 10-24 J

a broader range of frequencies.

Some lasers emit light in pulses that are only 10-12 s in duration. Compared to a laser that emits a steady, continuous beam of light, the Heisenberg uncertainty principle leads us to expect the photons from a pulsed laser to have lower energy. a narrower range of frequencies. higher energy. a broader range of frequencies. greater momentum.

1.04 × 10^11

The decay constant of a radioactive nuclide is 1.6 × 10-3 s-1. At a given instant, the number of atoms of the radioactive nuclide is 1.85 × 1012. The number of atoms of the nuclide that remain after a time interval of 30 minutes is closest to: 1.04 × 10^11 1.52 × 10^11 1.26 × 10^11 1.14 × 10^11 1.38 × 10^11

d.) The activity of the cobalt-60 sample will be greater.

The half-life of cobalt-60 is 5.3 years, while that of strontium-90 is 28 years. Suppose you have a sample of each, such that they initially contain equal numbers of atoms of these nuclides. How will the activities (number of decays per unit time) of the samples compare? a.) The activities cannot be compared without more information. b.) The activity of the strontium-90 sample will be greater. c.) The activities will be equal. d.) The activity of the cobalt-60 sample will be greater.

c.) There will be more strontium-90 than cobalt-60 nuclei.

The half-lives of cobalt-60 and strontium-90 are 5.3 years and 28 years respectively. Suppose that samples of cobalt-60 and strontium-90 are such that they initially have the same activity. What will be true of the numbers of cobalt-60 and strontium-90 nuclei in these samples? a.) There will be equal numbers of cobalt-60 and strontium-90 nuclei. b.) There will be more cobalt-60 than strontium-90 nuclei. c.) There will be more strontium-90 than cobalt-60 nuclei. d.) It is not possible to compare numbers of nuclei without knowing the masses of the samples.

A, C, D A. 12 orbital electrons. C. 12 protons. D. 18 neutrons.

The hypothetical atom 30/12 X contains (there may be more than one correct choice) A. 12 orbital electrons. B. 30 protons. C. 12 protons. D. 18 neutrons. E. 42 nucleons.

650 nm

The longest wavelength of a photon that can be emitted by a hydrogen atom, for which the initial state is n = 3, is closest to: 575 nm 550 nm 625 nm 650 nm 600 nm

a.) the cumulative repulsive force amongst the protons.

The primary reason very large nuclei are unstable is due to a.) the cumulative repulsive force amongst the protons. b.) the repulsive force between the neutrons and the protons. c.) the cumulative attractive force between the protons and the orbiting electrons.

I0/16

The radiation from a radioactive sample of a single isotope decreases to one-eighth of the original intensity in 30.0 years. What would the intensity be after 10.0 more years? I0/16 I0/32 I0/64

337 nm

The work function of a particular substance is 5.9 × 10-19 J. What is the photoelectric cutoff wavelength for this material? 219 nm 280 nm 394 nm 337 nm

2.80 eV

Upon being struck by 240 nm photons, a material ejects electrons with a maximum kinetic energy of 2.38 eV. What is the work function of this material? 2.80 eV 2.35 eV 3.70 eV 3.25 eV

6.42×1013 Hz

What is the frequency of the light emitted by atomic Hydrogen according to Balmer's formula with m = 6 and n = 11 ? 6.42×1013 Hz 3280 nm 4670 Hz 3.28×10−6 m

955 nm

What is the wavelength of the light emitted by atomic Hydrogen according to Balmer's formula with m = 3 and n = 8? 384 nm 955 nm 389 nm 1950 nm

The atomic number increases by 1.

When a beta minus decay occurs in an unstable nucleus, what happens to the atomic number of the nucleus? The atomic number increases by 1. The atomic number remains constant. The atomic number decreases by 1. The atomic number decreases by 2. The atomic number increases by 2.

The atomic number decreases by 1.

When a beta plus decay occurs in an unstable nucleus, what happens to the atomic number of the nucleus? The atomic number decreases by 2. The atomic number increases by 1. The atomic number increases by 2. The atomic number remains constant. The atomic number decreases by 1.

increases.

When a photon of light scatters off of a free stationary electron, the wavelength of the photon decreases. increases. remains the same. could either increase or decrease, depending on the initial energy of the photon.

44 protons and 54 neutrons.

When tellurium-98, 98/43 Te, undergoes β− decay, the daughter nucleus contains 42 protons and 36 neutrons. 56 protons and 42 neutrons. 44 protons and 54 neutrons. 54 protons and 44 neutrons.

c.) the number of electrons ejected per second

When the surface of a metal is exposed to blue light, electrons are emitted. If the intensity of the blue light is increased, which of the following will also increase? a.) the maximum kinetic energy of the ejected electrons b.) the time lag between the onset of the absorption of light and the ejection of electrons c.) the number of electrons ejected per second d.) all of the above e.) two of the above

a.) It is held together by the strong force that affects protons and neutrons, but not electrons.

Which of the following statements about the atomic nucleus are correct? (There may be more than one correct choice.) Check all that apply. a.) It is held together by the strong force that affects protons and neutrons, but not electrons. b.) The density of heavy nuclei is considerably greater than the density of light nuclei. c.) It has a typical radius on the order of 10-10 m. d.) Its volume is nearly the same for all atoms.

a.) In a good conductor, the highest-energy band containing electrons is only partially filled. d.) In a good conductor, two bands overlap so that unoccupied states are available.

Which of the following statements are true concerning a good conductor? Check all that apply. a.) In a good conductor, the highest-energy band containing electrons is only partially filled. b.) In a good conductor, the highest-energy band containing electrons is completely filled. c.) In a good conductor, two bands overlap so that no unoccupied states are available. d.) In a good conductor, two bands overlap so that unoccupied states are available.

a.) In a good insulator, the highest-energy band containing electrons is completely filled. c.) In a good insulator, the valence band is typically separated from the conduction band by 5 eV or more.

Which of the following statements are true concerning a good insulator? Check all that apply. a.) In a good insulator, the highest-energy band containing electrons is completely filled. b.) In a good insulator, the highest-energy band containing electrons is only partially filled. c.) In a good insulator, the valence band is typically separated from the conduction band by 5 eV or more. d.) In a good insulator, the valence band is typically separated from the conduction by less than 1 eV.

b.) The mass of the products of a nuclear fission reaction is less than the mass of the original elements. c.) Nuclear fission is the process during which a heavy nucleus splits into two intermediate-sized nuclei after being struck by a neutron.

Which of the following statements are true concerning nuclear fission reactions? Check all that apply. a.) The mass of the products of a nuclear fission reaction is greater than the mass of the original elements. b.) The mass of the products of a nuclear fission reaction is less than the mass of the original elements. c.) Nuclear fission is the process during which a heavy nucleus splits into two intermediate-sized nuclei after being struck by a neutron. d.) Nuclear fission is the process during which small nuclei combine to form a larger one.

a, b, f a.) A fusion reaction proceeds because the binding energy of the resulting nucleus is greater than the binding energy of the original nuclei. b.) The mass of the products of a nuclear fusion reaction is less than the mass of the original elements. f.) Nuclear fusion is the process during which small nuclei combine to form a larger one.

Which of the following statements are true concerning nuclear fusion reactions? Check all that apply. a.) A fusion reaction proceeds because the binding energy of the resulting nucleus is greater than the binding energy of the original nuclei. b.) The mass of the products of a nuclear fusion reaction is less than the mass of the original elements. c.) The mass of the products of a nuclear fusion reaction is greater than the mass of the original elements. d.) A fusion reaction proceeds because the binding energy of the resulting nucleus is less than the binding energy of the original nuclei. e.) Nuclear fusion is the process during which a heavy nucleus splits into two intermediate-sized nuclei after being struck by a neutron. f.) Nuclear fusion is the process during which small nuclei combine to form a larger one.

B and D B. They are emitted when electrons in complex atoms (those having a large atomic number) make transitions from higher shells to the K shell. D. The energy of x-ray photons is greater than the energy of visible-light photons.

Which statement about x rays is correct? A. Their wavelengths are greater than those of visible light. B. They are emitted when electrons in complex atoms (those having a large atomic number) make transitions from higher shells to the K shell. C. They are emitted when electrons in hydrogen make transitions from higher shells to the K shell. D. The energy of x-ray photons is greater than the energy of visible-light photons.

chain reaction

Which term describes a fission reaction in which more neutrons are given off than are needed to initiate the reaction? chain reaction fusion reaction critical reaction neutron catastrophe chemical reaction

c.) Neutrons dilute the electric repulsion of the protons.

Why do heavy nuclei contain more neutrons than protons? a.) Neutrons are lighter than protons. b.) Neutrons are heavier than protons. c.) Neutrons dilute the electric repulsion of the protons. d.) Neutrons are radioactive, and so are heavy nuclei.

28.28 Photorefractive keratectomy (PRK) is a laser-based surgery process that corrects near- and farsightedness by removing part of the lens of the eye to change its curvature and hence focal length. This procedure can remove layers 0.250 μm thick in pulses lasting 12.0 ns with a laser beam of wavelength 193 nm . Low-intensity beams can be used because each individual photon has enough energy to break the covalent bonds of the tissue. A.) In what part of the electromagnetic spectrum does this light lie? B.) What is the energy of a single photon? C.) If a 1.40 mW beam is used, how many photons are delivered to the lens in each pulse?

a.) ultraviolet