Modern Physics
For an atom of hydrogen where the quantum number n = 3, how many possible independent configurations of the atom exist (consider principal quantum number n, angular momentum quantum number l, magnetic quantum number ml, and magnetic spin quantum number ms)? 18 8 32 26 infinite
18 = 2n^2 n = 1, l = 0 s(1) n = 2, l = 1 p(3) n = 3, l = 2 d(5) n = 4, l = 3 f(7)
Use the Pauli exclusion principle to determine how many electrons can fill a single g sub-shell. 26 14 22 20 10
269 270
Scientists have made great strides towards unifying the fundamental forces of nature. At the time of the publishing of the text, the most unified of theories shows that the total number of forces to be fundamental in physics is 3 1 2 4 5
3 g, electroweak, Strong
Minimum energy of harmonic oscillator
> min potential energy of oscillator If they're equal, it would make both KE and Momentum = 0 (forbidden by uncertainty principle)
The spectacular image called "Einstein's Cross" is direct evidence of which of the following phenomenon. Light traveling faster than c. Black holes. Neutron stars. Gravitational bending of light.
Gravitational bending of light.
How did Planck modify the classical theory of blackbody radiation to correctly determine his radiation law? He found that the blackbody model was incorrect for purposes of theory He accepted the Stefan-Boltzmann law He assumed light was absorbed and emitted in quanta He realized that the charge of the electron was not quantized He proved the necessity of relativistic considerations
He assumed light was absorbed and emitted in quanta (discrete quantities)
How did Thomson measure the charge to mass ratio of the electron? He shot helium nuclei into a gold foil to measure the nuclei scattering against electrons within. He passed cathode rays through a magnetic field and measured the deflection. He suspended a drop of oil between electrodes to measure the electric field from the electrons. He measured very precisely a known quantity of hydrogen atoms and calculated the reduced mass ratio within each atom.
He passed cathode rays through a magnetic field and measured the deflection.
Who among the following persons did not play an important role in the discovery of the neutron? Henri Becquerel Walter Bothe and Herbert Becker James Chadwick Irene Curie and Frederic Joliot
Henri Becquerel Henri Becquerel = discover first radiation (alpha, beta particles) Bothe and Becker = penetrating radiation Chadwick = discovered Neutron Irene Curie and Frederic Joliot = Radioactive isotopes (penetrating radiation = neutron)
Which of the following statements best describes the line of stability? It has N = Z when A = 240. It has Z > N at A = 240 N always tends to be greater than Z. N tends to be greater than Z, especially for masses greater than calcium.
N tends to be greater than Z, especially for masses greater than calcium.
Karl Schwarzschild did all but one of the following during his relatively short life. Which one? Was a professor at German universities. Served in World War II for Germany in Russia. Found the radius of a collapsed star using the general theory of relativity. Was an astronomer.
Radius of blackhole Served in World War II for Germany in Russia.
The addition of velocities formula restricts the values of certain velocities due to all of the following EXCEPT: The curvature of spacetime consistent with inertial frames. Lorentz transformations. The speed of light in a vacuum is the same to all observers. The laws of physics are the same in all inertial frames.
The curvature of spacetime consistent with inertial frames.
Which of the following states of the hydrogen atom, as defined only by the principal quantum number, angular momentum quantum number, and magnetic quantum number, is allowed? n = 0, l = 2, ml = 1 n = 5, l = 2, ml = 3 n = 0, l = 1, ml = 2 n = 5, l = 2, ml = 0 n = 2, l = 2, ml = 0
n = 5, l = 2, ml = 0 n > 0, l < n, and l >= |ml|.
Joseph Weber is best known for Announcing the discovery of gravitational waves. First detecting the gravitational bending of light. Observing gravitational waves indirectly through the discovery of a binary system that includes a pulsar. Originated the LIGO project.
Announcing the discovery of gravitational waves
Frame dragging is a complex consequence of general relativity. It can be simplified into a classical analog, however, demonstrated by which of the following situations? A merry-go-round spins objects further from the center of rotation at faster linear speeds. A flamenco dancer's dress as she spins quickly a full turn. An elevator falling in a uniform gravitational field that has a hole in it to let light through. A rubber sheet with a heavy ball at rest and a rolling ball with its trajectory changed by the depression in the sheet. A figure skater in a spin moves her arms closer to her body and the rate of spin increases.
A flamenco dancer's dress as she spins quickly a full turn. Frame dragging is the affect on spacetime caused by non-static stationary distributions of mass-energy
What is the most accurate physical analog for a particle in a box? A guitar string A rope driven with a sinusoidal oscillation on one end and fixed on the other end A pan-flute pipe (open on both ends) An organ pipe open on only one end A jump rope with a girl on each end driving the end to a rhythm
A guitar string
In which of the following cases would you expect degeneracy of the first excited state? Hint: Make sure to consider all three dimensions. A neutral helium atom initially in its ground state in a magnetic field. A particle trapped inside a sphere of radius R. A particle trapped inside a three dimensional box of lengths L1 > L2 > L3. Identical particles, with one in an infinite square-well potential and the other in a finite square-well potential with walls of potential V0 high but of the same width as the infinite potential well.
A particle trapped inside a sphere of radius R.
The shape and size of a nucleus can best be described as A perfect sphere of diameter 0.4 nm. A perfect sphere of diameter 4 * 10-18 m. A roughly spherical shape of diameter 4 x 10-18 m. A roughly spherical shape of diameter 4 fm.
A roughly spherical shape of diameter 4 fm.
The "liquid drop model" of the nucleus allowed von Weizsäcker to propose his equation for a semi-empirical mass formula. This formula includes all of the following EXCEPT: A correction for nuclear surface interactions being different than interior saturated interactions. A term providing for the repulsion of protons in the nucleus. A term proportional to the total number of nucleons. A term for the energy associated with the fact that most stable nuclei prefer to have N approximately equal to Z. A term incorporating the instability of protons within the nucleus.
A term incorporating the instability of protons within the nucleus.
Which of the following statements best describes the Franck-Hertz experiment? Alpha particles slam into gold foil to measure the recoil angle. Light incident on a metal surface ejects electrons and the more energetic ones establish a current. Accelerated electrons collide with atoms in a gas and excite them. A strong electric field tears electrons off of atoms in a gas to establish a current. Passing electrons through a magnetic field to separate electrons with different spin components.
Accelerated electrons collide with atoms in a gas and excite them.
The de Broglie wavelength of which of the following objects would be smallest if the objects all had the same momentum? Electron. Proton. Tennis ball. Bowling ball. All the same wavelength.
All the same wavelength.
Alpha decay occurs in some radioactive nuclides with A > 150. The probability of an alpha particle being emitted depends on the energy of the alpha particle. Why is this so? Wave functions for the alpha particle must decrease to zero when the strong force potential goes to zero. Alpha particles must pass through classically forbidden regions with high potential barriers. The Coulomb potential for the alpha particle depends on the energy of the alpha particle. To emit the alpha particle, the nucleus must be hit by a gamma ray that has energy inversely proportional to the probability it will strike the nucleus.
Alpha particles must pass through classically forbidden regions with high potential barriers. The energy of the alpha particle is independent of the Coulomb potential of the particle
For an atom of hydrogen without the effects of an external magnetic field, an electron transition from the 3P subshell to the 2P subshell is called a forbidden transition. Why is this so? Electrons in hydrogen are forbidden from transitioning in that way due to peculiarities unique to solutions of Schr�dinger's equation for hydrogen. The normal Zeeman effect prohibits certain transitions from occurring. Since the electron at low energies must pass through the nucleus, nuclear effects prevent certain transitions to orbits through the nucleus. An atom that changes energy through transitioning must either absorb or emit a photon.
An atom that changes energy through transitioning must either absorb or emit a photon SEE pp. 260-261 Zeeman effect?
When you interchange your emitter for one with a smaller work function, you measure An increased current A decrease in the necessary stopping voltage An increase in the necessary stopping voltage No change in either current or stopping voltage Either a or c. You cannot determine which from the information given.
An increase in the necessary stopping voltage I is already established. thus going to a lower work function with photons that have more energy will need a higher necessary stopping voltage Decreased work function, greater energy photons 104-106, 109-110
When you increase only the frequency of the incoming light onto the emitter, you measure An increased current A decrease in the necessary stopping voltage An increase in the necessary stopping voltage No change in either current or stopping voltage Either a or c. You cannot determine which from the information given.
An increase in the necessary stopping voltage Increase in frequency, higher KE to electrons, higher voltage needed to bridge the emitter-collector gap
When you increase only the intensity of the light onto the emitter, you measure A decrease in the necessary stopping voltage An increase in the necessary stopping voltage No change in either current or stopping voltage Either a or c. You cannot determine which from the information given. An increased current
An increased current more photos hit emitter, more electrons freed and given E to jump the gap, current will increase Most energetic electrons have current
Bohr found that the total angular momentum of the hydrogen atom was L = n(hbar), but this prediction was incorrect. Choose the statement below that best explains why. The Zeeman effect prevents certain orientations of L. Bohr's semiclassical planetary model of the atom did not include space quantization of angular momentum. Bohr's restrictions allowed for a state where L = 0, while this is quantum mechanically forbidden by the uncertainty principle. Bohr's model allowed the electrons to pass through the nucleus as well as orbiting around it.
Bohr's semiclassical planetary model of the atom did not include space quantization of angular momentum.
The de Broglie wavelength of which of the following objects would be smallest if the objects had the same velocity? Electron. Proton. Tennis ball. Bowling ball. All the same wavelength.
Bowling ball. lambda = planck/momentum
What is the bremsstrahlung process? The emission of a photon from an electron being accelerated by a nucleus The emission of an electron from a metal when light is shined on it Thermal excitation of photons in a substance The emission of an electron from an inner electron shell and the resulting photon when an electron drops from an outer shell to take its place Converting power-producing nuclear material to weapons grade
Breaking or slowing radiation The emission of a photon from an electron being accelerated (change speed and direction) by a nucleus
Although it seems intuitive that electrons in atoms should fill the 1s shell, 2s shell, 2p shell, 3s shell and so on in order of principal quantum number and orbital angular momentum quantum number, this is not the case. For instance, the 4s sub-shell fills before the 3d sub-shell. Which of the following statements does NOT help explain why this occurs? Electrons fill the lowest energy levels available to them. Sub-shells with low l values have more elliptical orbits, spend more time inside the filled shells, and are at lower energies. Sub-shells with higher l values spend less time inside the filled shells and have higher energies. Electrons fill sub-shells by order of the sub-shells with least total electrons first, then sub-shells with greater number of total electrons. Electrons in shells with higher energy generally experience less shielding of nuclear charge.
Electrons in shells with higher energy generally experience less shielding of nuclear charge. The sub-shells at higher energies usually have more shielding from nuclear charge
Choose the statement below that does NOT help explain why the ionization energy of cadmium is so much larger than that of indium. The energy required to remove an electron from a filled sub-shell is much larger than the energy required to remove an electron from a nearly empty sub-shell. The atomic radius of indium is larger than that of cadmium. Electrons in the 4d sub-shell spend more time inside the closed shells than does the additional 5p electron and therefore are more shielded. The additional electron in the 5p sub-shell is at higher energy and therefore easier to remove from the atom.
Electrons in the 4d sub-shell spend more time inside the closed shells than does the additional 5p electron and therefore are more shielded.
Which of the following statements is true about the spin-orbit coupling effects on the transitions of an atom such as sodium? Assume sodium is modeled by a single electron atom. The difference in the energy of a split state does not depend on the electron's angular momentum, but instead the angular momentum of the nucleus. The differences in energy level transitions are significant enough to change the order of filling of the sub-shells. Electrons with a state of l = 0 never have split energy levels. For single electron atoms (or atoms with one electron outside a filled shell) each nl state is made a doublet.
Electrons with a state of l = 0 never have split energy levels.
Which of the following are assumed when analyzing photons involved in Compton scattering? Momentum, but not energy, is conserved when the photon scatters from an electron. The photon always recoils with significant energy lost to the electron. The photon behaves like a wave and diffracts at an angle from the electron. Scattering from tightly bound electrons always produces the photons with greatest wavelength change. Energy and momentum are treated relativistically in the scatter
Energy and momentum are treated relativistically in the scatter The speed and momentum of the electron are not large enough before or after the impact with relation to the photon to treat them relativistically. Compton did not, and calculations that do not treat this problem relativistically match with experiment.
Which of the following does not result from applying the Schrodinger equation to the electron in the hydrogen atom? Finding the Bohr radius. Deriving the correct energy level dependence. Finding the probability distribution functions for the electron in the hydrogen atom Defining the rules restricting the quantum numbers n, l, and ml Finding the value of the intrinsic spin quantum number of the electron
Finding the value of the intrinsic spin quantum number of the electron
Maxwell's equations utilize or can produce all of the following EXCEPT: Formulations for magnetic monopoles Vector functions for electric and magnetic fields A formulation where the speed of light can be calculated Quantities of charge and current Permeability and permittivity of a vacuum
Formulations for magnetic monopoles
Using the restrictions set forth by the uncertainty principle, which of the following combinations of values is it possible to know simultaneously? I. momentum vector II. momentum magnitude III. momentumZ IV. momentumX V. momentumY VI. angular momentum quantum number VII. magnetic quantum number I, II, III, IV, V, VI, VII I, III, VI, VII II, III, VI, VII III, IV, VI, VII
II, III, VI, VII Magnetic quantum is dependent on angular momentum quantum momentumZ depends on magnetic quantum number total angular momentum depends on angular momentum quantum number
Which of the following statements is NOT true about the expectation value of a physical observable? It is calculated from wave functions. It is usually near in agreement with experimental results. It can be calculated for energy, momentum, and position. It is best described as a probable average of many measurements. It can only be found after normalizing the wave functions involved.
It can only be found after normalizing the wave functions involved.
Which of the following statements is most correct about the uncertainty principle? It is impossible to know exactly both the position and the momentum of a particle simultaneously. An electron with some momentum can be trapped into an arbitrarily small box. Our instruments will eventually be able to measure more precisely than the principle presently allows. On large length scales, the uncertainty principle dominates our understanding of the physical world. A particle limited in space can occupy any energy.
It is impossible to know exactly both the position and the momentum of a particle simultaneously.
Which of the following statements is not true about x-ray scattering (in crystals) and its importance? It showed that electromagnetic radiation diffracts and interferes like a wave. It ruled out the corpuscle model of light. It helped uncover the crystalline structures of many solids. It helped scientists more accurately measure x-ray wavelengths. Rosalind Franklin used the scattering to model molecules of DNA.
It ruled out the corpuscle model of light. All others are true
Which of the following phenomena is not associated with light retardation? A measurement by the NASA Cassini spacecraft in 2003. A measurement by the Viking spacecraft on Mars in 1976. Light moving near a large object takes a longer path due to spacetime curvature. Light reflected by mirrors left on the moon by astronauts.
Light moving near a large object takes a longer path due to spacetime curvature.
Which of the following scientists is most directly responsible for ushering in the communications age in the 20th century? Galileo Newton Maxwell Michelson Carnot
Maxwell
Who first accurately measured the value for the charge of the electron? Rontgen Thomson Planck Millikan Einstein
Millikan: Oil drop experiment (Trapping oil between two electrodes which the electric force was acting against gravity)
Who established the atomic number of an atom as more important than the atomic weight, thus reorganizing the periodic table? Moseley. Mendeleev. Rutherford. Einstein. Brown.
Moseley. Characteristic x-rays spectra determined number of protons was the most important factor in ordering the periodic table
Which of the following is an important difference between the infinite square-well potential and the finite square-well potential? Particles can exist in classically forbidden regions outside the finite square-well potential. The number of energy levels is limited in the infinite square-well potential but not limited in the finite square-well potential. The infinite square-well potential utilizes Schr�dinger's equation to describe particle motion while the finite square-well potential does not. The energy levels are quantized only in the finite square-well potential. Only the energy levels in the finite square-well potential depend on Planck's constant.
Particles can exist in classically forbidden regions outside the finite square-well potential.
10. Using Maxwell's equations, the speed of light can be calculated using which of the following fundamental physical constants?
Permeability and permittivity
Which of the following statements about blackbody radiation is NOT correct? The wavelength of peak relative intensity emitted from a blackbody depends on 1/T, the temperature of the blackbody. The power per unit area given by blackbody radiation depends on T^4. The classical theory of intensity vs. wavelength, the Rayleigh-Jeans formula, of blackbody radiation is only correct at large wavelengths. Planck's radiation law for intensity vs. wavelength of blackbody radiation depends on 1/lambda^5 and T^4.
Planck's radiation law for intensity vs. wavelength of blackbody radiation depends on 1/lambda^5 and T^4. 101
When you encounter a calculation where the integral sum of the ___________ of the particle being somewhere in space is greater than ___________, then the problem is most likely caused by lack of _________. Fill in the missing words. Wave function, the normalization, probability Normalization, the probability, causation Boundary conditions, 0, normalization Probability, 1, normalization Probability, 0, wave function
Probability, 1, normalization
Some elements like iron, cobalt, and holmium make very good natural magnets. Which of the following statements best describes why? Selection rules for multi-electron atoms tend to maximize electron spin and orbital angular momentum. Atoms in the crystalline structure of the solid metal tend to antialign their spin and orbital angular momentum. Large numbers of paired electron spins are essential to good magnets. The filled s shells with high n and paired electrons create larger atomic radii and therefore the electrons can contribute more to the magnetic field.
Selection rules for multi-electron atoms tend to maximize electron spin and orbital angular momentum.
Mimicking the experiment of Geiger and Marsden, you fire alpha particles of about 5 MeV into an unknown target and measure the scattering angle. Which of the following is likely to affect the scattering angle of the alpha particles coming off of the target? The temperature of the target. The number of electrons orbiting the nuclei of the target. The Coulomb force between the alpha particle and the electrons in the target. The Coulomb force between the alpha particle and the nuclei of the target.
The Coulomb force between the alpha particle and the nuclei of the target. In coulomb force, the massive, positive nucleus of the target interacting with alpha particle determines scattering angle
The disintegration energy for gamma decay of a nucleus is typically on the order of 10-100 keV and can even be on the order of MeV. Which of the following statements best describes why the energies are so much larger than from atoms? Energy levels within the nucleus are spaced farther apart than atomic levels. The spins of the paired protons and neutrons within the nucleus are aligned within energy levels. The higher energies of the gamma rays are higher in probability of emission because they must tunnel through classically forbidden regions. All nuclei are only metastable, increasing binding energy exponentially when the nucleus is in an excited state. The Coulomb attraction within the nucleus places it lower in energy, therefore greater excitation energies are necessary.
The Coulomb force only repels protons within the nucleus Stronger nuclear reactions = E levels spaced farther apart
A highly reliable laser emits a steady beam of light at a fixed frequency f that hits a photodetector a light year away in what we can assume is empty space. The laser/detector setup is now placed as a system with a black hole directly behind the laser. What happens to the frequency of the light beam? The detector measures the frequency of the beam as less than f. The detector measures the frequency of the beam as greater than f. The laser emits light at a frequency less than f (as measured at the laser) The laser emits light at a frequency greater than f (as measured at the laser) Both a and c
The detector measures the frequency of the beam as less than f. gravitational redshift: Wavelength is lengthened due to gravity = lower frequency
The energy levels of a single-electron atom (or the approximation for one electron outside of a filled shell) can be split due to a relationship between the spin and the orbital angular momentum. Choose the statement that best explains why this occurs. The electron is affected by the magnetic field of the proton, which in the rest frame of the electron is seen as orbiting the electron. There is a state with lesser energy when the spin magnetic moment of the electron and internal magnetic field of the atom are aligned. Only in an external magnetic field do the energy levels split due to spin-orbit coupling. Only in an external electric field do the energy levels split due to spin-orbit coupling. The total angular momentum component in the z-direction is not quantized and can take on any value as a sum of orbital and spin angular momentum.
The electron is affected by the magnetic field of the proton, which in the rest frame of the electron is seen as orbiting the electron.
Why is the Schrodinger equation so much simpler to solve for electrons in atoms like H and He+ than for Na or even B+? The strong force and Coulomb forces are nearly in balance for the smaller atoms. The electrons in larger atoms affect each other by Coulomb repulsion. Nuclear charge is distributed in significantly larger volume in larger atoms and therefore the Coulomb force is diminished on the electrons. Gravity affects each electron of larger atoms more, making the approximation of only Coulomb potential grossly inaccurate. More principal quantum numbers are allowed for all electrons in the larger atoms.
The electrons in larger atoms affect each other by Coulomb repulsion Multiple electrons makes it much more complicated
Following selection rules for multi-electron atoms, imagine a titanium atom in the ground state with two electrons in each of the 3d and 4s shells. In the 3d shell, which of the following scenarios is least likely to be true? The electrons orbital angular momentum is aligned. The electrons' spins are anti-aligned to minimize energy. The spin and angular momentum of the electrons are aligned to minimize energy. The energy levels of the electrons are split due to LS coupling. The magnetic quantum numbers of the electrons are either both positive or both negative.
The electrons' spins are anti-aligned to minimize energy. Hund's rule: orbitals in a group are singly occupied before they can be double. All electrons have same spin to maximize energy
Which of the following is not necessary as a boundary condition for a wave function? The wave function must approach a finite number or zero over any limit. The wave function must be a function for each of the dimensions it depends on (single-valued for each variable independently). The wave function must approach zero when x -> ± infinity The wave function must approach zero as x -> L, where L is a boundary where V-> infinity The first derivative of the wave function must approach zero when approaching all regions of potential energy V > 0.
The first derivative of the wave function must approach zero when approaching all regions of potential energy V > 0.
Astronomers have identified more and more black holes in recent years by using x-ray imaging. If black holes are supposed to be black and not emit light, where are the x rays coming from? The accretion disk is full of accelerating atoms, which emit electromagnetic radiation as they accelerate. The friction within the accretion disk heats the gas to very high temperatures, and the gas emits x rays according to its characteristic spectrum. Hawking radiation not captured by the black hole knocks out K shell electrons within the accretion disk and the matter emits characteristic x rays. Scientists suspect that many of the supposed black holes are indeed neutron stars that emit x-ray radiation. Gravitational waves coming from the black hole are thought to interact with matter in the accretion disk, exciting many of the atoms into producing x rays.
The friction within the accretion disk heats the gas to very high temperatures, and the gas emits x rays according to its characteristic spectrum. Radiation comes from superheated gas in orbit falling into the black hole
Davisson and Germer used a nickel crystal for their scattering experiments that had been modified when they tried to repair it. Which of the following describes the major change from before they tried to repair it and afterward that allowed them to work on the groundbreaking experiments they did? The oxidation of the nickel from immediately after it was taken from a vacuum environment introduced impurities with intermediate band gaps. The heating processes created larger crystals, which allowed them to clearly see the electron diffraction. Under the intense heat of their repair process, the electrons were scattered off of energetically oscillating nickel atoms, whereas before they hit the stationary lattice atoms. Their knowledge of the new nickel crystals led them to believe that electrons with low energy (on the order of ~10 eV) only would scatter off of the closely spaced nickel atoms.
The heating processes created larger crystals, which allowed them to clearly see the electron diffraction. Davisson and Germer = arrangement of the atom, larger crystals, see diffractions more clearly
Which of the following statements is correct about the experiment that first measured the charge of the electron? The oil drop is suspended because there are no forces acting on the drop The important result was that Coulomb attraction made all of the oil drops the same mass, regardless of type of oil The mass of the drop was determined by measuring its terminal velocity The value for electron charge had an experimental error of about 35% Light hitting the oil drops manipulated their movement in a way to create an interference pattern.
The mass of the drop was determined by measuring its terminal velocity Vt occurs when frictional drag force (dependent on velocity) balances with gravity Radius of drop is dependent on Vt and density can give mass
In his calculations, Bohr came across a number now called the "Bohr radius". This number is 5.29 * 10^-11 m and is The maximum radius of the hydrogen atom. The minimum radius of the hydrogen atom. The average radius of the hydrogen atom. The minimum radius of atoms of all elements. The maximum radius of atoms of all elements.
The minimum radius of the hydrogen atom. Ground state radius (most tightly bound)
Which of the following statements is not true about wave packets and their use in describing particles? A wave packet is fundamentally a region over which a number of waves of different frequencies and amplitudes are added together to form a non-zero result. An important property of a wave packet describing a particle is the superposition of many different waves. The particle can be described using Fourier series and a Fourier integral. The movement and travel of a wave packet is governed by their grouping order. An important property of a wave packet describing a particle is the localization of wave amplitude.
The movement and travel of a wave packet is governed by their grouping order.
Which of the following reasons explains why the neutrino must exist? The neutrino is a product of gamma ray decay. The neutrino is necessary to allow for the correct spin angular momentum conservation in a nuclear disintegration. The neutrino is necessary to carry away a charge in a nuclear disintegration. The neutrino is the force carrier that holds together quarks within protons and neutrons. The neutrino decays into electrons and protons in an unstable nucleus.
The neutrino is necessary to allow for the correct spin angular momentum conservation in a nuclear disintegration.
What did Rutherford's famous scattering experiment help to prove in his day? The nucleus of an atom is positively charged. The nucleus of an atom takes up a large portion of the space in an atom. The scattering with the gold foil could either be due to a single interaction with a nucleus or multiple interactions with electrons. Alpha particles are neutral and massive. Thomson's model was essentially correct.
The nucleus of an atom is positively charged.
Protons in the nucleus attract electrons with enough electromagnetic force to keep them in orbit at high speeds. Protons in general repel each other, but in the nucleus they are bound together. How is this possible? The introduction of neutrons diffuses the protons' charge over a large volume The strong force binds the protons together on small distance scales The electrons orbiting the nucleus create an electromagnetic force on all sides due to their high speed of revolution The gravitational force binds the protons together on small distance scales The electroweak force binds the protons together on small distance scales
The strong force binds the protons together on small distance scales
In attempting to describe the atom, Bohr made a set of general assumptions. Which of the following statements is NOT a result or closely aligned with those general assumptions (the assumptions might not be quantum mechanically correct)? The radius of a hydrogen atom can be calculated from a certain combination of fundamental constants. Electrons in the hydrogen atom transfer between quantized energy states and can exist nowhere else in the atom but in these energy states. The velocity of the electron around the nucleus is the same in all orbits, although the shape of the orbit changes with higher values of n, the principal quantum number Stationary states are states where the electron accelerates around the nucleus but does not emit electromagnetic radiation.
The velocity of the electron around the nucleus is the same in all orbits, although the shape of the orbit changes with higher values of n, the principal quantum number Radius of the hydrogen atom can be calculated using Planck's constant, the elementary charge, the electron mass, and the permittivity of vacuum Velocity of electron changes with principal quantum number
Which of the following is true about Bragg planes? There is only one Bragg plane for any given crystal structure. They are especially useful for detecting transitions between energy levels in the crystals' atoms. They are used to scatter alpha particles in gold and other materials. They are evenly spaced planes within crystal structures of atoms. All of the above.
They are evenly spaced planes within crystal structures of atoms. 2dsin(theta) = 2lambda
Which of the following best describes nuclear forces? They are short ranged. They go to zero at r = 0. They are long ranged like the Coulomb force. They are charge dependent.
They are short ranged.
In quantum mechanics there is a process by which an electron can start in a region of relatively weak forces, enter a classically forbidden region, and then reemerge on the other side of that region. The electron, it can be said, travels through a "wall." How do scientists commonly refer to this process? Boring Bremsstrahlung Spontaneous fission Correspondence Tunneling
Tunneling
Which of the following is a consequence of the laws of thermodynamics? Heat can be completely changed into work Heat transfers from a cold object to a hot object until equilibrium is reached Atoms can be at any temperature, even absolute zero Work can be completely changed into heat
Work can be completely changed into heat
A particle moves along the x-axis in the positive direction with energy E. It encounters a barrier with potential V > E at x = 0 and extending to x = L. Is there any chance for the particle make it to the other side? Yes. The wave functions allow for a small probability for the particle to pass through the barrier. Yes, but only if the particle increases in energy so that E > V. Yes. The particle will pass by unaffected in both classical and quantum mechanical consideration. No. An incoming particle would have negative kinetic energy within the potential barrier. No. The particle will transmit some energy but the particle will always reflect off the barrier.
Yes. The wave functions allow for a small probability for the particle to pass through the barrier.
The relativistic factor ( used in conjunction with the Lorentz transformation provides that an object of length L measured in a frame at rest is measured to be L when that object is moving with respect to the rest frame. if two frames are aligned at t = t' = 0 but the 'primed' frame moves at some constant velocity, an interval of time t in the rest frame will be measured as a time t/ in the moving frame. increased velocities decrease the value of a particle moving faster than the speed of light gives an imaginary relativistic factor.
a particle moving faster than the speed of light gives an imaginary relativistic factor.
Stern and Gerlach performed an experiment that showed the space quantization of silver atoms in an inhomogeneous magnetic field. Their experiment demonstrated that space quantization is a property that only exists for energy levels, governed by quantum number n. the number of ml states was even, not governed by the factor (2l + 1) as thought previously. the differences in magnetic moment of the atom demonstrated space quantization in external magnetic fields. the classically defined Bohr magneton was inaccurate because it did not take into account the space quantization of external magnetic fields within the atom. an additional angular momentum factor within the atom was causing the observed space quantization.
an additional angular momentum factor within the atom was causing the observed space quantization. :the intrinsic spin of the electron
An electron approaches a positron. They annihilate and produce two photons, which fly off at the speed of light in opposite directions. Analyze the situation using relativistic momentum and energy and choose the false statement below. If the resulting photons have the same wavelength, then the electron and positron must have had equal momenta. The kinetic energies of the positron and electron determine the frequency of the gamma rays produced in the annihilation. The rest energies of the positron and electron determine the frequency of the gamma rays produced in the annihilation. The photons can have the same wavelength, but it is not necessary. There can be two photons produced (as in the above example), but only one photon can is produced in some cases.
annihilate: positron + electron = 2 protons There can be two photons produced (as in the above example), but only one photon can is produced in some cases. Does not conserve linear momentum
Both the classical and quantum mechanical probability densities predict for a simple harmonic oscillator that the probability of the particle being at that location will be greatest at regions of greatest potential energy. the particle has a finite probability of being in a region with V > E, where E is the total energy of the system. at very large values of n (the number of energy state), the particle will most likely be detected furthest from the equilibrium position within its classically defined range of motion the minimum energy of the oscillating particle is zero
at very large values of n (the number of energy state), the particle will most likely be detected furthest from the equilibrium position within its classically defined range of motion Bohr's correspondence principle
The Rydberg equation is used to determine the ratio of the electron charge to its mass calculate the wavelengths of different spectral lines of hydrogen measure the mass of the hydrogen atom calculate the wavelengths of different transitions in energy level of electrons in helium
calculate the wavelengths of different spectral lines of hydrogen Predicts values for different transition energy levels in the hydrogen atom
The nuclear force can be all of the following EXCEPT: short-range saturable spin dependent
charge dependent
When de Broglie's matter waves are applied to electrons in the Bohr atom, which of the following occurs? The electron is found to have in its orbit an integral number of half-wavelengths. Bohr's quantization assumption for electron orbits is modified to incorporate the wave properties of the electron. de Broglie's results allow an integral number of wavelengths in the electron orbits. The angular momentum of the electron in the atom is constant, with longer wavelengths at larger quantum numbers.
de Broglie's results allow an integral number of wavelengths in the electron orbits. Quantized the same way de Broglie is quantized.
Gravitational and inertial masses are equal and have been thought of as such only in the past century. only when isolated from experimentation. only when isolated from the ability to tell whether a frame is in a uniform gravitational field or under constant acceleration. due to the equivalence principle. only when space is not curved.
due to the equivalence principle Equivalence principle: no experimentation can tell the difference in a closed area, between uniform gravitational field (gravitational mass), or constant acceleration (inertial mass)
Characteristic x-ray spectra come from bremsstrahlung processes for electrons close to the nucleus. electrons transitioning down from an outer shell replace electrons ejected from an inner shell. random excitations of electrons when atoms are near room temperature. photons scattering off of electrons, thereby losing energy and emitting radiation.
electrons transitioning down from an outer shell replace electrons ejected from an inner shell. The difference in binding energies produces a photon
Scattering one unknown particle of Z1 off of another, much more massive target particle of Z2, you observe a certain number of particles scattered at an angle (Theta + deltaTheta) (your detector is of width deltaTheta , at an angle Theta from the beam axis, centered at an angle Phi around the beam axis). Use Rutherford's scattering equation (and assumptions) to determine which of the following changes to the experiment would be most likely to increase the number of particles you detect with your detector. increase the velocity of the scattering particles. increase the angle around the beam axis. increase the cross section of the target nuclei. increase the number of neutrons in the scattering nuclei. increase the number of electrons in the target nuclei.
increase the cross section of the target nuclei. Refer to the ****ing ginormous equation
When relating the linear momentum and total energy of an object with speed v = 0.8c, which of the following changes would increase the energy by the greatest amount? Assume that it is possible to change the mass of the object. increase the momentum of the object to 2p while keeping the mass constant. increase the mass of the object to 2m while keeping the momentum constant. imagine the speed of light to change to 82% of its present value (the object is still at initial speed v). increase the momentum of the object to 2p while keeping the velocity constant. increase the speed of the object to 0.95c.
increase the momentum of the object to 2p while keeping the velocity constant.
Hawking radiation explains how stars gravitationally collapse to form black holes. causes the short lives of black holes. is due to one particle from particle-antiparticle pairs. explains the accretion disks around black holes. provides for an event horizon.
is due to one particle from particle-antiparticle pairs. If gravity is stronger than the outward pressure of the stars core, the star will collapse Black holes have long half lives particle-antiparticle pairs that would annihilate almost immediately. Accretion disks around black holes is explained by large gravitational attraction of black holes (Stars and their outter layers are pulled in) Gravitational and mass energy relationship of star provides for event horizon (escape velocity is larger than speed of light)
The mass of the deuteron is exactly the sum of the neutron and proton mass. is slightly less than the sum of the neutron and proton mass. is exactly 2.000000 u. is exactly the sum of a neutron, proton, and electron mass.
is slightly less than the sum of the neutron and proton mass.
The planetary model of the atom was fundamentally flawed. It failed theoretically because: a perfectly circular orbit would violate the laws of gravitation. electrostatic attraction would not be sufficient to keep the electron/nucleus in a bound state. it predicted positive and negative charge equally distributed throughout the atom. it was well established experimentally that accelerating electrons emit electromagnetic radiation. it did not provide for the existence of neutrons.
it was well established experimentally that accelerating electrons emit electromagnetic radiation. Planetary model meant that the electron orbiting the nucleus had to be in constant acceleration and constantly emit radiation. This would mean that the electron would keep losing energy and fall into the nucleus.
The uncertainty principle prevents one from knowing both the ____________ and the _________ for a certain particle to arbitrary precision at the same time. What are the two correct missing words? localization in interval of time; energy energy; momentum localization in interval of time; position energy; range of angular frequencies momentum; range of wave number
localization in interval of time; energy
A small sphere of initial volume V is filled with n moles of helium at initial pressure and temperature P and T. Which of the following statements is true? n/2 moles of gas are removed, the volume is decreased to V/2, and the pressure decreases to P/4 with a drop in temperature of T/2 The volume decreases to V/2, and the pressure increases to 4P when the temperature is T/2 n moles of gas are added, the total sample is heated to 2T, and the pressure drops to P/2 when the volume increases to 8V The amount of gas is doubled to 2n, the pressure is doubled to 2P, and the volume is doubled to 2V, with a corresponding temperature drop to T/2
n moles of gas are added, the total sample is heated to 2T, and the pressure drops to P/2 when the volume increases to 8V
The gyromagnetic ratio: is 1 for the magnetic moment associated with the spin and 2 for the magnetic moment associated with the angular momentum. relates the Bohr magneton to the elementary charge. does not help explain the result of the Stern and Gerlach experiment. relates the magnetic moments of spin and angular momentum to the total angular momentum. gives the values of intrinsic spin quantum number of the electron as 1/2 and -1/2
relates the magnetic moments of spin and angular momentum to the total angular momentum. page 257
By the early part of the 20th century, theoretical physics had changed dramatically because of so many new results. The work of Franck and Hertz showed that the atomic levels were quantized. Why did that work specifically make so much of an impact at that time? More and more scientists rejected their findings and reaffirmed the triumphs of classical physics. Their work moved science to the discovery of hydrogen as an element. It affirmed that quantum physics triumphed over classical physics in key cases. They showed that when using large length scales, quantum effects dominate. All of the above.
t affirmed that quantum physics triumphed over classical physics in key cases. it affirmed Planck's work to be true
Which of the following would not have significant effect on the probability distribution of position of an electron (in a given combination of quantum numbers) in the hydrogen atom? the angle theta the azimuthal angle probability distribution the spherical harmonic for that combination of angular momentum and magnetic quantum numbers the radial wave equation for that combination of principal and angular momentum quantum numbers the distance from the nucleus
the azimuthal angle probability distribution 241, 244, 246
Phase velocity is the maximum transverse velocity of a point on a wave, when the particle is moving fastest in each period of oscillation. the velocity of a point on the wave at a given phase. always half the group velocity in a wave packet. always greater than the particle's velocity when the particle is described in terms of de Broglie matter waves. unrelated to the energy of the wave
the velocity of a point on the wave at a given phase. = center of mass for particles
One major difference between Young's double slit interference experiment with light and Jonsson's similar experiment with electrons is that the electrons exhibited an interference pattern only characteristic of particles and the light exhibited an interference pattern only characteristic of waves. the light must be at low intensity to produce the interference pattern while the electrons could be propelled onto the slits at very high frequency and still produce the pattern. the wavelengths of the electrons were much smaller than that of light and therefore the slits for the electron experiment were much more difficult to produce. For the electrons, the slit widths could be larger than for those of photons because of the electrons' larger momenta.
the wavelengths of the electrons were much smaller than that of light and therefore the slits for the electron experiment were much more difficult to produce.