ASTRO-1 CH.5 HW
Which of the following statements is true of green grass?
It absorbs red light and reflects green light.
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.)
The blue star has a hotter surface temperature than the red star.
From laboratory measurements, we know that a particular spectral line is formed by the rotation of the carbon monoxide molecule (CO) and it appears at a wavelength of 2.6007 millimeters (mm). The spectrum of an interstellar cloud of gas shows the same CO line appearing at a wavelength of 2.6008 mm. What can we conclude about the gas cloud?
The cloud is moving away from us.
A spectral line that appears at a wavelength of 321 nm in the laboratory appears at a wavelength of 328 nm in the spectrum of a distant object. We say that the object's spectrum is:
Redshifted
Which is hotter?
A blue star
Radio waves are
A form of light.
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?
They have a frequency of 2 hertz.
The color of Mars in our sky is determined by the ______ of Mars's spectrum.
Visible portion
The absorption line spectrum shows what we see when we look at a hot light source (such as a star or light bulb) directly behind a cooler cloud of gas. Suppose instead that we are looking at the gas cloud but the light source is off to the side instead of directly behind it. In that case, the spectrum would __________.
Be an emission line spectrum
The _____ allows us to determine how fast Mars is moving toward or away from us.
Doppler effect
Compared to red light, blue light has higher frequency and
Higher energy and shorter wavelength
Why does Mars appear reddish in color?
It reflects most of the Sun's red light while absorbing most of its blue light.
Hot gas in Mars's upper atmosphere produces _____ in the ultraviolet portion of its spectrum.
Emission lines
How are wavelength, frequency, and energy related for photons of light?
Longer wavelength means lower frequency and lower energy.
Rank the forms of light from left to right in order of increasing speed. To rank items as equivalent, overlap them.
SAME SPEED
We know how fast a star in the galaxy is moving away from us on the basis of its
Spectrum
The simplified spectra for four stars is shown here. Which star has the lowest temperature?
Star D (purple line)
Study the graph of the intensity of light versus wavelength for continuous spectra, observing how it changes with the temperature of the light bulb. Recall that one of the laws of thermal radiation states that a higher-temperature object emits photons with higher average energy (Wien's law). This law is illustrated by the fact that for a higher temperature object, the graph peaks at __________.
A shorter wavelength
Which statement about photons of light is true?
An infrared photon has less energy than an X-ray photon, but travels at the same speed.
The spectrum of Star A has an absorption line of hydrogen at 660.0 nm. The spectrum of Star B has an absorption line at 666 nm. The wavelength of this transition in the laboratory is 656.2 nm. What can I say about Star A and B?
Both stars are moving away from me, Star B is faster than Star A.
Doppler shifted hydrogen absorption lines are seen in the spectrum of a star. The hydrogen line at 656.28 nm is seen to be shifted to 656.08 nm. Is the star moving towards or away from us, or can we not tell?
Moving towards us
Click "show" for the emission line spectrum, then click "choose gases" and study the emission line spectrum for neon. The neon "OPEN" sign appears reddish-orange because __________.
Neon atoms emit many more yellow and red photons than blue and violet photons
We know the Sun is primarily made from hydrogen and helium on the basis of its
Spectrum.
Suppose that Mars had a higher surface temperature. How would its spectrum be different?
The peak in the infrared would be at shorter wavelength.
Which of the following describes the light that can be detected from a person?
The person reflects many wavelengths of visible light and emits a continuum of wavelengths of infrared light.
If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?
The planet is rotating.
We determine Mars's surface temperature from the peak wavelength of the_____ it emits.
Thermal radiation
What type of visible light spectrum does the Sun produce?
An absorption line spectrum
Which object is likely to be the coldest? The object whose light spectrum is brightest in the
Infrared
Lines of a particular element appear at the same wavelength in both emission and absorption line spectra.
True
The energy levels for electrons vary from one element to another.
True
Carbon dioxide in Mars's atmosphere produces ______ in the infrared portion of its spectrum.
Absorption lines
When an electron in an atom goes from a lower energy state to a higher energy state, the atom can
Absorb a photon of a specific frequency. Submit
