Q&A Hero

Q: The helium in a child's balloon is composed of A) former alpha-particle. B) former beta particles. C) both of these D) neither of these

Q: The most harmful radiations are those that A) kill living cells. B) damage living cells. C) don't encounter cells.

Q: Cosmic rays originate in the A) Earth's interior. B) Earth's upper atmosphere. C) Sun. D) cosmos. E) none of the above

Q: The main source of Earth's natural heat is A) molten-hot lava. B) pressure on Earth's interior. C) radioactivity in Earth's interior. D) solar energy in the form of fossil fuels.

Q: The natural background radiation we personally encounter is A) a trace amount. B) about a quarter. C) about half. D) more than half.

Q: Most of the radioactivity we personally encounter originates from A) fallout from testing of nuclear weapons. B) nuclear power plants. C) medical X-rays. D) the natural environment.

Q: The radiation source closest to us originates in A) medical treatments. B) all kinds of power plants. C) our own bodies. D) none of the above

Q: Human damage is usually highest for radiation by A) beta particles. B) alpha particles. C) either of the above D) none of the above

Q: Radiation dosages based on potential damage is in A) rads. B) rems. C) joules. D) none of the above

Q: Radiation dosage is commonly measured in A) rads. B) rems. C) joules. D) none of the above

Q: Radioactivity in the world is something A) relatively new. B) as old as the world itself. C) to become frantic about.

Q: Which experiences the least electrical force in an electric field? A) alpha particle B) beta particle C) electron D) gamma ray E) all the same

Q: Which experiences the greatest electrical force in an electric field? A) alpha particle B) beta particle C) electron D) gamma ray E) all the same

Q: Which will NOT bend when moving in a magnetic field? A) alpha particle B) beta particle C) gamma ray D) all bend the same

Q: Rays with the shortest wavelengths have the A) highest frequencies and energies. B) lowest frequencies and energies. C) lowest frequencies but highest energies.

Q: Which wavelengths are shortest? A) light ray B) X-ray C) gamma ray

Q: Which of these will penetrate into lead? A) alpha particle B) beta particle C) gamma ray. D) all of the above

Q: Alpha particles and beta particles are deflected by a magnetic field in A) opposite directions. B) perpendicular directions to each other. C) the same direction.

Q: Which radiation has no association with electric charge? A) alpha B) beta C) gamma D) all of the above E) none of the above

Q: Gamma rays are emitted by way of A) ionizing radiation. B) transitions within an atom's innermost electrons. C) transitions within the atomic nucleus. D) none of the above

Q: The sources of both X-rays and gamma rays are A) electron clouds. B) the atomic nucleus. C) both of these D) neither of these

Q: Which is heated in its interior by nuclear processes? A) Sun B) Earth C) both of these D) neither of these

Q: A sample of highly-radioactive material is somewhat A) warmer than the environment. B) cooler than the environment. C) neither of these

Q: The high temperature of Earth's interior is mainly due to A) great internal pressure. B) friction, as plates move past one another. C) the Earth's natural heat. D) radioactive processes.

Q: The sources of X-rays are A) electron clouds. B) the atomic nucleus. C) both of these D) neither of these

Q: X-rays are similar to A) alpha rays. B) beta rays. C) gamma rays. D) all of the above E) none of the above

Q: X-rays are emitted by way of A) ionizing radiation. B) transitions within an atom's innermost electrons. C) transitions within the atomic nucleus. D) none of the above

Q: X-rays may be correctly regarded as A) high frequency sound waves. B) high frequency radio waves. C) both of these D) none of these

Q: By scattering alpha particles from gold, Rutherford showed the atomic nucleus to be very A) small relative to the atom. B) massive relative to the mass of an electron. C) both of these D) neither of these

Q: According to the correspondence principle, a new theory must A) overlap and agrees where the old theory works. B) account for confirmed results from the old theory. C) predict the same correct results as the old theory. D) all of the above E) none of the above

Q: A new theory conforms to the correspondence principle when it A) corresponds to all theories in nature. B) updates the essence of the old theory. C) connects two or more theories. D) accounts for verified results of the old theory.

Q: The correspondence principle applies to A) theories of submicroscopic phenomena. B) theories of macroscopic phenomena. C) all good theories.

Q: Unlike Bohr, Schrdinger viewed electrons as A) fixed in position. B) traveling in circles. C) tiny bullets. D) waves.

Q: Using the Schrdinger equation, scientists can calculate A) probabilities. B) the position of an electron. C) the velocity of an electron. D) all of the above

Q: The thing that "waves" in the Schrdinger equation is a A) particle's position. B) particle's momentum. C) wave function. D) all of the above E) none of the above

Q: The Schrdinger equation is most useful for describing A) submicroscopic particles. B) microscopic particles. C) macroscopic particles. D) none of the above

Q: A hypothetical atom has four distinct energy states. Assuming all transitions are possible, the number of spectral lines this atom can produce is A) 5. B) 6. C) 7. D) 8. E) more than 8.

Q: Compared with the wavelengths of visible light, the wavelengths of matter waves in atoms are relatively A) long. B) short. C) neither, for all are the same.

Q: The probability cloud for the electron in the hydrogen atom has an average radius A) quite different from the radius predicted by Bohr. B) in agreement with the orbital radius of Bohr. C) as yet not accurately measured.

Q: A stable electron orbit cannot exist if its circumference is A) a single wavelength. B) 2 wavelengths. C) 2.5 wavelengths. D) any of the above E) none of the above

Q: In the electron-wave model of the atom, an electron in the second energy level contains A) a single wavelength. B) two wavelengths. C) any number of wavelengths. D) none of the above

Q: In the electron-wave model of the atom, the orbit of an electron in the ground state contains A) a single wavelength. B) multiple wavelengths. C) even number quanta.

Q: The finding that electrons occupy discrete orbits in an atom was first explained by the A) quantization of electric charge. B) small mass of the electron. C) circumference of each orbit being an integral multiple of an electron wavelength. D) none of the above

Q: A beam of electrons has A) wave properties. B) particle properties. C) both of these D) neither of these

Q: Discrete radii and energy states of atoms were first explained by electrons circling the atom in an integral number of A) wave frequencies. B) de Broglie wavelengths. C) diffraction patterns. D) high-speed particles. E) none of the above

Q: Quantization of electron energy states in an atom is better understood in terms of the electron's A) wave nature. B) particle nature. C) neither of these

Q: According to de Broglie, destructive interference occurs when an orbiting wave A) reinforces itself B) doesn't reinforce itself. C) neither of these

Q: According to de Broglie, constructive interference occurs when an orbiting wave A) reinforces itself B) doesn't reinforce itself. C) neither of these

Q: The finding that electrons in an atom occupy a volume much greater than the volume of the nucleus is best explained by A) electromagnetic forces. B) angular momentum conservation. C) relative sizes of electrons and nuclei. D) the wave nature of the electron. E) none of the above

Q: The discreteness of orbits of electrons in an atom are due to A) wave interference. B) momentum conservation. C) electric charge quanta D) all the above E) none of the above

Q: The discreteness of energy levels is best understood by considering the electrons to be A) like tiny planets orbiting a sun. B) attached to the nucleus by massless springs. C) much less massive than the nucleus. D) all of the above E) none of the above

Q: Two spectral lines in a spectrum have frequencies of 2.0 x 1014 Hz and 4.6 x 1014 Hz. A higher-frequency line in the same spectrum likely has a frequency of A) 2.6 x 1014 Hz. B) 6.6 x 1014 Hz. C) 13.2 x 1014 Hz. D) none of the above

Q: According to the Bohr model, an electron in an excited state of hydrogen can emit A) at most a single photon until the atom re-excites. B) several photons in a series of transitions to a lower state. C) a continuous stream of light. D) none of the above

Q: Physicists today consider the Bohr model of the atom to be A) an accurate picture of a hydrogen atom. B) totally useless of historical interest only. C) oversimplified, but nevertheless useful.

Q: Why electrons don't spiral into atomic nuclei is best explained by their A) particle nature. B) wave nature. C) both of these D) neither of these

Q: A problem with the Bohr model of the atom is that electrons circling the nucleus A) accelerate and should continuously emit radiation. B) lose energy and should spiral into the nucleus. C) both of these D) neither of these

Q: The Bohr model of the atom is akin to a A) miniature solar system. B) blob of plum pudding, where raisins represent electrons. C) central heavy ball with lighter balls connected by springs. D) all of the above

Q: The Ritz combination principle states that the sum of the A) frequencies of two lines in a spectrum often equal the frequency of a third line. B) energies associated with two lines in a spectrum often equal the energy associated with a third line. C) energy transitions of quantum jumps is consistent with the conservation of energy. D) all of the above E) none of the above

Q: What was discovered in atomic spectra by physics pioneers Balmer, Rydberg, and Ritz? A) unexplained randomness B) mathematical order C) all atoms are about the same size D) electrons occupy well-defined shells about the atomic nucleus E) electrons behave as standing waves

Q: An excited atom decays to its ground state and emits a photon of red light. If instead the decay is to an intermediate state, then the light emitted could be A) red. B) violet. C) blue. D) any of these E) none of these

Q: An excited atom decays to its ground state and emits a photon of green light. If instead the decay is to an intermediate state, then the light emitted could be A) red. B) violet. C) blue. D) any of the above E) none of the above

Q: The rule stating that the sum of two emitted frequencies in an atomic spectrum equals a third frequency is consistent with A) momentum conservation. B) energy conservation. C) Planck's constant. D) none of the above

Q: The rule stating that the sum of two emitted frequencies in an atomic spectrum equals a third frequency is attributed to the physicist A) Niels Bohr. B) Max Planck. C) W. Ritz. D) Einstein

Q: When an electron de-excites from the third quantum level to the second, and then to the ground state, two photons are emitted. The sum of the emitted frequencies equals the frequency of the single photon that would be emitted if de-excitation were from the third to A) the second level. B) the ground state. C) any other level. D) none of the above

Q: An excited hydrogen atom is capable of emitting radiation of A) a single frequency. B) three frequencies. C) many more than three frequencies.

Q: When an electron drops from a higher energy level to a lower one, energy is emitted. In comparison, how much energy is required to reverse the process, going from the lower level to the higher level? A) less energy B) the same energy C) more energy

Q: Spectral lines for an element are often in the A) infrared region. B) ultraviolet region. C) both of these D) neither of these

Q: The spectral lines of atomic spectra are A) images of the slit in a spectroscope. B) orderly, and even predictable. C) as an identity of atoms as fingerprints are of people. D) all of the above E) none of the above

Q: Credit for research in our knowledge of atomic spectra includes A) Johann Jacob Balmer. B) Johannes Rydberg. C) Walter Ritz. D) all of the above E) none of the above

Q: What did Millikan measure in his oil-drop experiment? A) the electric charge of an electron B) the mass of an electron C) the mass of oil drops D) none of the above

Q: When Millikan observed oil drops hovering at rest in his chamber, he knew that A) an upward electric force balanced the weight of each drop. B) each drop was in mechanical equilibrium. C) the net force on each drop was zero. D) all of the above E) none of the above

Q: Millikan was able to stop falling oil droplets in their paths by A) opposing electric and gravitational forces. B) magnetic repulsion. C) both of these D) neither of these

Q: The beam in a cathode-ray tube is composed of A) photons. B) electrons. C) both of these D) neither of these

Q: A beam of electrons can be deflected by a A) magnetic field. B) electric field. C) both of these D) neither of these

Q: Both electrons and protons have equal-magnitude A) mass. B) charge. C) energy. D) all of the above E) none of the above

Q: A beam of electrons is employed in A) a gold-foil experiment. B) a cathode-ray tube. C) a LED television screen. D) an oil-drop experiment.

Q: Credit for research in our knowledge of the electron includes A) William Crookes. B) J.J. Thomson. C) Robert Millikan. D) all of the above E) none of the above

Q: The first to be credited for assigning the terms positive and negative to electricity was A) William Crookes. B) J.J. Thomson. C) Robert Millikan. D) Benjamin Franklin. E) none of the above

Q: Some alpha particles fired at a gold foil bounced backward as a result of A) reflection from the surfaces of gold atoms. B) electrostatic repulsion by gold nuclei. C) electrostatic repulsion by electrons within gold atoms. D) all of the above E) none of the above

Q: Some alpha particles pass through gold foil with very little deflection mainly because the A) electric field is zero inside the foil. B) atoms of gold are mostly empty space. C) net charge of the gold atoms is zero. D) all of the above E) none of the above