5 Written questions
5 Matching questions
- Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond. You notice that it does two full up and down bobs each second. Which statement is true of the ripples on the pond?
A) They have a frequency of 4 hertz.
B) They have a frequency of 2 hertz.
C) We can calculate the wavelength of the ripples from their frequency.
D) They have a wavelength of two cycles per second.
- Briefly explain why spectral lines are useful in determining the chemical composition of their source.
- How can an electron in an atom lose energy to go from a higher energy level to a lower energy level?
A) It loses kinetic energy.
B) It releases a photon equal in energy to its own energy drop.
C) It absorbs a photon equal in energy to its own energy drop. D) It loses gravitational potential energy.
E) It exchanges gravitational potential energy for kinetic energy.
- Suppose you look at a spectrum of visible light by looking through a prism or diffraction grating. How can you decide whether it is an emission line spectrum or an absorption line spectrum?
A) An emission line spectrum consists of bright lines on a dark background, while an absorption line spectrum consists of dark lines on a rainbow background.
B) An emission line spectrum consists of a long bright line, while an absorption line spectrum consists of a long dark line.
C) The only way to decide is to make a graph of the intensity of the light at every wavelength, and then analyze the graph carefully.
D) The emission line spectrum is produced by electrons jumping up in energy level, while the absorption line spectrum is produced by electrons jumping down in energy level.
- Which of the following statements about X rays and radio waves is not true?
A) X rays travel through space faster than radio waves.
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.
- a A) An emission line spectrum consists of bright lines on a dark background, while an absorption line spectrum consists of dark lines on a rainbow background.
- b B) It releases a photon equal in energy to its own energy drop.
- c A) X rays travel through space faster than radio waves.
- d Every chemical element has a unique set of atomic energy levels and therefore a unique set of spectral lines. Thus, by identifying spectral lines, we can identify the elements that produced them.
- e A) Power is the rate at which energy is used, so its units are a unit of energy divided by a unit of time.
5 Multiple choice questions
- A) 4 electrons
- A) angle of incidence = angle of reflection
- C) the filter transmits red light and absorbs other colors.
5 True/False questions
Suppose the surface temperature of the Sun were about 18,000 K, rather than 6,000 K. How much more thermal radiation would the Sun emit? How would the thermal radiation spectrum of the Sun be different? → 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.
Compared to the volume of its nucleus, the volume of an atom is about
A) the same.
B) a thousand times greater.
C) a million times greater.
D) a billion times greater.
E) a trillion times greater. → E) a trillion times greater.
Define atomic weight (or atomic mass). → False
Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?
A) Star X is moving away from us faster than Star Y.
B) Star Y is moving away from us faster than Star X.
C) Star X is hotter than Star Y.
D) Star X is moving away from us and Star Y is moving toward us. → The ice melts into liquid, then evaporates into gas. At higher temperatures, the water molecules dissociate atoms. At very high temperatures, the atoms are ionized.
Which of the following statements about electrical charge is true?
A) Two negative charges will attract each other.
B) Two positive charges will attract each other.
C) A positive charge and a negative charge will repel each other.
D) A positive charge and a negative charge will attract each other. → D) A hot object emits more total radiation per unit surface area than a cool object.