Suppose two observers look at the spectrum of a cloud of gas in a laboratory; the first reports seeing emission lines and the second reports absorption lines. Explain. 1) Only the first observer sees the gas against a hot background 2) Only the second observer sees the gas against a hot background. 3) One observer is moving rapidly relative to the other. 4) The atoms in the gas are forming molecules.
Atoms of different elements have unique spectral lines because each element 1) has atoms of a unique color. 2) has a unique set of neutrons. 3) has a unique set of electron orbits. 4) has unique photons.
Atoms have particular associated spectral lines because 1) electrons have only certain allowed orbits. 2) light consists of waves. 3) light waves can show the Doppler effect. 4) speed of light in a vacuum is a constant.
In the Sun, the transition from level 4 to level 2 of hydrogen produces photons with a wavelength of 486.1nm. In a star twice as hot as the Sun, this transition would produce photons with 1) half that wavelength. 2) the same wavelength. 3) twice that wavelength. 4) four times that wavelength.
Here is the spectrum of a mystery star: Which elements are present? 1.Calcium only 2.Calcium and hydrogen 3.Magnesium and calcium 4.Calcium, hydrogen, and magnesium
Here is the spectrum of a mystery star: Which elements are present? 1.Calcium only 2.Calcium and hydrogen 3.Magnesium and hydrogen 4.Calcium, hydrogen, and magnesium
THE SPECTRAL SEQUENCE Class SpectrumColorTemperature O ionized and neutral helium, weakened hydrogen bluish31,500-49,000 K B neutral helium, stronger hydrogen blue-white10,000-31,500 K A strong hydrogen, ionized metals white7500-10,000 K F weaker hydrogen, ionized metals yellowish white6000-7500 K G still weaker hydrogen, ionized and neutral metals yellowish5300-6000 K K weak hydrogen, neutral metals orange3800-5300 K M little or no hydrogen, neutral metals, molecules reddish2100-3800 K L no hydrogen, metallic hydrides, alkalai metals red-infrared1200-2100 K T methane bandsinfraredunder 1200 K