A typical atom has a size of about(^ is symbol for power)
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1 Angstrom (10^-10 meters).
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An atomic nucleus has a size of about(^ is symbol for power)
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1 Angstrom (10^-10 meters).
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Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon?
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its wavelength and energy
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Which of the following describes the light that can be detected from a person?
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The person reflects many wavelengths of visible light and emits a continuum of wavelengths of infrared light
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Which of the following is not a way light and matter interact?
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evaporation
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Suppose you see two stars a blue star and a red star. Which of the following can you conclude about the two stars? Assume that no Doppler shifts are involved. (Hint Think about the laws of thermal radiation.)
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The blue star has a hotter surface temperature than the red star.
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When an electron in an atom goes from a higher energy state to a lower energy state, the atom
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emits a photon of a specific frequency.
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When an electron drops to a lower energy level in an atom,
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light at a wavelength specific to the change in energy levels is emitted.
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How are wavelength, frequency, and energy related for photons of light?
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Longer wavelength means lower frequency and lower energy.
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You and I are emitting primarily
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infrared radiation.
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When considering light as made up of individual "pieces," each characterized by a particular amount of energy, the pieces are called ________.
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photons
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According to the laws of thermal radiation, hotter objects emit photons with ________.
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a shorter average wavelength
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How can an electron in an atom lose energy to go from a higher energy level to a lower energy level?
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It releases a photon equal in energy to its own energy drop.
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If a material is transparent, then it
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transmits light well.
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The spectra of most galaxies show redshifts. This means that their spectral lines ________.
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have wavelengths that are longer than normal
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Which of the following statements about thermal radiation is always true?
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A hot object emits photons with a higher average energy than a cool object.
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From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 121.6 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 121.8 nm. What can we conclude?
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The star is moving away from us
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Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. What is its atomic number and atomic mass number?
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The atomic number is 79, and the atomic mass number is 197.
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If you heat a gas so that collisions are continually bumping electrons to higher energy levels, when the electrons fall back to lower energy levels the gas produces
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an emission line spectrum.
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Everything looks red through a red filter because
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the filter transmits red light and absorbs other colors
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Which of the following is an example of reflection or scattering?
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Red light hits a red sweatshirt.
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From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation?
