Shared Flashcard Set

Details

Test #1 Review
Homework questions to review for the test.
40
Astronomy
10/11/2011

Additional Astronomy Flashcards

 


 

Cards

Term
A gas heated to millions of degrees would emit
Definition
mostly x rays
Term
An atom of the element iron has an atomic number of 26 and an atomic mass number of 56. If it is neutral, how many protons, neutrons, and electrons does it have?
Definition
26 protons, 30 neutrons, 26 electrons
Term
An electron-volt is
Definition
an amount of energy much smaller than a joule
Term
Compared to the size of its nucleus, the size of an atom is about
Definition
one hundred thousand times greater
Term
Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. What is its atomic number and atomic mass number?
Definition
The atomic number 79 and the atomic mass number is 197
Term
Currently the largest optical telescope mirrors have a diameter of
Definition
10 m
Term
Everything looks red through a red filter because
Definition
the filter transmits red light and absorbs other colors
Term
From laboratory measurements we know that a particular spectral line formed by hydrogen appears at a weavelength of 121.6 nm. The spectrum of a particular star shows the same hudrogen line appearing at a wavelenght of 121.8 nm. what can we conclude?
Definition
The star is moving away from us.
Term
From lowest energy to highest energy, rank the different categories of electromagnetic radiation.
Definition
RADIO INFRARED VISIBLE LIGHT ULTRAVIOLET X-RAYS GAMMA RAYS
Term
How are wavelength, frequency, and energy related for photons of light?
Definition
Longer wavelenght means lower frequency and lower energy
Term
How can an electron in an atom lose energy to go from a higher energy level to a lower energy level?
Definition
It releases a photon equal in energy to its own energy drop
Term
How do we estimate the surface temperature of a star?
Definition
By optaining its spectrum and classifying the spectral type (color0
Term
How many atoms fit across the period at the end of this sentence?`
Definition
millions
Term
If a material is transparent then it
Definition
transmits light well
Term
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
Definition
the planet is rotating
Term
If you heat a gas so that collisions are continually bumping electrons to higher energy levels, when the electrons fall back to lower energy levels, the gas produces
Definition
an emission line spectrum
Term
Imagine a planet like Earth orbiting the Sun, but in an orbit with an average distance of 2 AU. What is the orbital period
Definition
2.8 years
Term
In what part of the electromagnetic spectrum do the biggest telescopes on on Earth operate
Definition
radio
Term
In what wavelenght range was interferometry first routinely used
Definition
radio
Term
Spectra from neutral atoms compared with spectra from ionized atoms of the same element
Definition
have different sets of spectral lines
Term
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)
Definition
The blue star has a hotter surface temperature than the red star
Term
The energies of two photons you might detect emitted by hydrogen atoms are 10.2 and 2.1 eV. Which photon has the longest wavelength.
Definition
The 2.1 eV photon
Term
The largest effective telescope, created by radio interferometry, is the siz of
Definition
Earth
Term
The frequency of a wave is
Definition
AOTA
Term
The wavelength of a wave is
Definition
The distance between two adjacent peaks and the wave
Term
We are measuring the spectra of two hydrogen gas clouds. The laboratory frame wavelength of one hydrogen line is 656.2 nm. Cloud A's emission line wavelength is 660.1 nm and Cloud B's emission line wavelength is 670.1 nm. What can we conclude about these clouds?
Definition
They are both receding from us, and Cloud B is receding faster than Cloud A.
Term
We can see each other in the classroom right now because we
Definition
reflect visible light.
Term
When an atom loses an electron, it becomes
Definition
ionized.
Term

When an electron in an atom goes from a higher energy state to a lower energy state, the atom
Definition
emits a photon of a specific frequency.
Term
Which of the following is not a way light and matter interact?
Definition
evaporation
Term

Which of the following is not a good reason to place observatories on remote mountain tops?
Definition

to be able to observe at radio wavelengths
Term

Which of the following objects is not a close approximation of a thermal emitter?
Definition
hot, thin gas
Term
Which of the following statements about X-rays and radio waves is not true?
Definition
Neither X-rays nor radio waves can penetrate Earth's atmosphere.
Term
Which of the following statements about electrical charge is true?
Definition
A positive charge and a negative charge will attract each other.
Term
Which of the following statements about electrons is not true?
Definition
Electrons orbit the nucleus rather like planets orbiting the Sun.
Term

Which of the following statements about thermal radiation is always true?
Definition
A hot object emits photons with a higher average energy than a cool object.
Term

Which of the following wavelength regions cannot be studied with telescopes on the ground?
Definition
both B and C
Term

Why do astronomers need different telescope designs to observe across the electromagnetic spectrum?
Definition
Photons of different energy behave differently and require different collection strategies.
Term

Without telescopes or other aid, we can look up and see the Moon in the night sky because it
Definition
reflects visible light.
Term
You and I are emitting primarily
Definition
infrared radiation.