Bhavna Gundamaraju
LIGHT AND ATOMS
1. Use the hypothetical atom drawings (A-F) below to answer the next five questions. Note that there is
only one correct answer choice for each question and each choice is used only once.
a. Which shows the absorption of violet light? Explain your reasoning.
i. Atom D shows the absorption of violet light because there is a high energy difference
between the two levels which needs high energy light photons and the absorption of a
short wavelength of light.
b. Which shows the emission of blue light? Explain your reasoning.
i. Atom C shows a shorter wavelength emission which can only be satisfied by blue light
because of the energy level jump from n=3 to n=1.
c. Which shows the absorption of green light? Explain your reasoning.
i. Atom C shows an intermediate energy shift, putting it into the green wavelength.
d. Which shows the emission of orange light? Explain your reasoning.
i. Atom E shows far and long wavelengths involving n=4 and n=2 transitions, meaning
that orange light would likely be found here.
e. Which shows an electron being ejected from the atom?
i. Atom A shows an electron being ejected from the electron energy levels altogether,
rather than being moved from one level to the other, so it’s likely being ejected from
the atom.
2. Consider the situations shown (A-D):
a. In which situation will the observer receive light that is shifted to shorter wavelengths?
i. When the star is moving towards the observer, like in situation C.
b. Will this light be blue shifted or red shifted for this case?
i. It will be blueshifted.
c. What direction is the star moving relative to the observer for this case?
i. The star is moving towards the observer in this case.
d. In which situation will the observer receive light that is shifted to longer wavelengths?
i. When the star is moving away from the observer, like in situation B.
e. Will this light be blue shifted or red shifted for this case?
i. No, it will be red shifted.
f. What direction is the star moving relative to the observer for this case?
i. The star is moving away from the observer in this case.
3. In which of the situations shown will the observer receive light that is not Doppler shifted at all? Explain
your reasoning.
a. A and D would be the situations in which the observer will receive light that is not shifted at all.
4. Imagine our solar system is moving in the Milky Way toward a group of three stars. Star A is a blue star
that is slightly closer to us than the other two. Star B is a red star that is farthest away from us. Star C is a
yellow star that is halfway between Stars A and B.
a. Which of these three stars, if any, will give off light that appears to be blueshifted? Explain your
reasoning.
i. All three stars will give off light that appears to be blue shifted because the stars will
appear to be moving towards us. In this case, the Milky Way is the one moving toward
