5 Written questions
5 Matching questions
- Emission lines from different ionization states of the same element appear in the same place in the spectrum
- The most common isotope of gold has atomic number 79 and atomic weight 197. How many protons and neutrons does the gold nucleus contain? Assuming the gold is electrically neutral, how many electrons does it have? If the gold is triply ionized, how many electrons does it have?
- Spectra from neutral atoms compared with spectra from ionized atoms of the same element
A) are the same.
B) are slightly redshifted.
C) are slightly blueshifted.
D) have different sets of spectral lines.
E) have the same sets of spectral lines but different widths for those lines.
- Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?
A) The cloud is extremely hot.
B) The cloud is visible primarily because it reflects light from nearby stars.
C) The cloud is cool and very dense, so that you cannot see any objects that lie behind it.
D) The cloud is cool and lies between you and a hot star.
- 1) If you have a 100-watt light bulb, how much energy does it use each minute?
A) 6,000 joules
B) 6,000 watts
C) 600 joules
D) 600 watts
E) 100 joules
- a D) The cloud is cool and lies between you and a hot star.
- b False
- c A) 6,000 joules
- d The most common isotope of gold contains 79 protons and 118 neutrons. If it is neutral, it also contains 79 electrons. If the gold is triply ionized instead, it is missing 3 electrons and so has only 76 electrons.
- e D) have different sets of spectral lines.
5 Multiple choice questions
- A) Electrons orbit the nucleus rather like planets orbiting the Sun.
- From the first rule of thermal radiation, we know that tripling the temperature of an object increases the amount of thermal radiation it emits per unit area by a factor of 34 = 81. Thus, increasing the surface temperature of the Sun from 6,000 K to 18,000 K would increase its thermal radiation by a factor of 81. The higher temperature of the Sun would shift the peak of its thermal radiation spectrum from its current place in the visible light region into the ultraviolet. The hotter Sun would emit more energy at all wavelengths, with the greatest output coming in the ultraviolet.
- C) an emission line spectrum.
- By comparing the wavelength of the spectral lines in the object's spectrum to the rest wavelengths of the same lines, we measure the Doppler shift. This tells us the object's radial motion: A shift toward shorter wavelength means the object is moving toward us, and a shift to longer wavelength means it is moving away from us. We cannot learn anything about the object's tangential motion from its spectral lines because this does not affect the line positions.
- A) hot, thin gas
5 True/False questions
From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation?
A) infrared, visible light, ultraviolet, X rays, gamma rays, radio
B) radio, infrared, visible light, ultraviolet, X rays, gamma rays
C) visible light, infrared, X rays, ultraviolet, gamma rays, radio
D) gamma rays, X rays, visible light, ultraviolet, infrared, radio
E) radio, X rays, visible light, ultraviolet, infrared, gamma rays → B) radio, infrared, visible light, ultraviolet, X rays, gamma rays
You observe a distant galaxy. You find that a spectral line of hydrogen that is shifted from its normal location in the visible part of the spectrum into the infrared part of the spectrum. What can you conclude?
A) The galaxy is moving away from you.
B) The galaxy is moving towards you.
C) The galaxy has very weak gravity.
D) The galaxy is made purely of hydrogen. → A) The galaxy is moving away from you.
If we say that a material is opaque to ultraviolet light, we mean that it ________.
A) absorbs ultraviolet light
B) emits ultraviolet light
C) transmits ultraviolet light
D) reflects ultraviolet light → C) ion
Thermal radiation is defined as ________.
A) radiation with a spectrum whose shape depends only on the temperature of the emitting object
B) radiation produced by an extremely hot object
C) radiation that is felt as heat
D) radiation in the form of emission lines from an object → A) radiation with a spectrum whose shape depends only on the temperature of the emitting object
Which of the following statements about X rays and radio waves is not true?
A) Neither X rays nor radio waves can penetrate the earth's atmosphere.
B) X rays have shorter wavelengths than radio waves.
C) X rays and radio waves are both forms of light, or electromagnetic radiation.
D) X rays have higher frequency than radio waves.
E) X rays have higher energy than radio waves. → A) Neither X rays nor radio waves can penetrate the earth's atmosphere.