Date post: | 19-Dec-2015 |
Category: |
Documents |
View: | 215 times |
Download: | 1 times |
REMINDERS
• Exam II next Thursday, April 14!
• Practice exam will be posted on website - Same format as first exam –
Multiple Choice & Short Answer
• Review session (Q & A only) Tuesday, April 12 @ 7 pm
Location: normal lecture hall in Physics
Discussion Review Plan
1. Study techniques suggestions
2. Chapters covered
3. Main equations to know (partial list!)
4. Key things to know (partial list!)
5. Practice discussion questions
6. Practice multiple choice
Study Techniques
• Take notes on your notes – make summary sheets
• Make these into flash cards & study (not just definitions and equations – concepts, too!) Draw pictures!
• Having these things will make studying for the final easier
• Think about possible essay questions and be prepared for them!
Material Covered
• Chapter 5 – Light, interaction with matter, telescopes
• Chapter 10 – The Sun • Chapter 11 – Stars – overview / properties• Chapter 12 – Stellar evolution• Chapter 13 – Deaths of stars
• Textbook, lecture notes, discussion section activities!
Equations to Be Familiar With(may be an incomplete list!)
E = hc / λ photon
T ~ 1 / λ peak
distance = 1 / parallax angle
Luminosity, L ~ R2T4
Brightness or Flux, F ~ L / (distance)2
Key Things to Know:(definitely an incomplete list!)
• Equations already mentioned• EM spectrum – order of wavelength
regions• Types of spectra & how they are formed• Doppler Effect• Structure of our SUN• H fusion – (4 H → 1 He + energy +
neutrinos)• Spectral types, OBAFGKM
Key Things to Know (continued):
• Binaries – how to get masses, which are stable?
• HR diagram – be able to draw it and label
• Life cycle of low & high mass stars
• Hydrostatic Equilibrium
• Stellar mass cutoffs – 2M, 8 M, 1.4 M, 3 M
(M is the mass of the Sun)
The electromagnetic spectrumFigure 3.5
Identify the following portions of theElectromagnetic spectrum:
A B D EC
The electromagnetic spectrumFigure 3.5
Which end of the spectrum is more energetic, A or B? Why?
A B
If the Hydrogen
gas cloud is moving towards
Earth, the absorption line marked will shift in
which direction?
BA
An absorption line of Hydrogen measured at rest
How do light and matter interact?KNOW THESE DEFINITIONS!
• Emission
• Absorption
• Transmission
• Reflection or Scattering
What types of light spectra can we observe?
1. Continuous spectra
2. Absorption spectra
3. Emission spectra
REMEMBER!
Luminosity of a star is intrinsic.
Depends on Temperature & Radius.
L ~ R 2 T 4
Flux changes with distance.F ~ L / d2
Doppler Effect Summary
Motion toward or away from an observer causes a
shift in the observed wavelength of light:
• blueshift (shorter wavelength)
motion _______ you
• redshift (longer wavelength) motion AWAY
from you
• greater shift greater speed
Doppler Effect Summary
Motion toward or away from an observer causes a
shift in the observed wavelength of light:
• blueshift (shorter wavelength) motion toward
you
• redshift (longer wavelength)
motion ______ from you
• greater shift greater speed
How do telescopes help us learn about the universe?
• Telescopes collect more light than our eyes
light-collecting area
• Telescopes can see more detail than our eyes angular resolution
• Telescopes/instruments can detect light that is invisible to our eyes (e.g., infrared, ultraviolet)
Is it on FIRE?
Which is the correct explanation for the sun’s shining?
Is it CONTRACTING?
Is it powered by NUCLEAR ENERGY?
The balance of the inward force of gravity with the outward force of pressure due to radiation is referred to as ?
Sun releases energy by fusing four hydrogen nuclei into what?
What will the next fusion product be?
?
IN4 protons
OUT4He nucleus2 positrons
2 gamma rays2 _______????
Total mass is 0.7% lower
Where does it go?
Solar Thermostat
Temperature Restored
Temperature Decreases
Fusion Rate (Increases or Decreases)?
Core (compresses or expands)?
A difference between an ultraviolet photon and a radio photon is that
• A. the energy of the radio photon is
greater
• B. only the radio photon is an
electromagnetic wave
• C. only the ultraviolet photon is an
electromagnetic wave
• D. the energy of the ultraviolet photon is greater
• E. none of the answers are correct
A difference between an ultraviolet photon and a radio photon is that
• A. the energy of the radio photon is
greater
• B. only the radio photon is an
electromagnetic wave
• C. only the ultraviolet photon is an
electromagnetic wave
• D. the energy of the ultraviolet photon is greater
• E. none of the answers are correct
The speed of a radio wave is
• A. the speed of sound
• B. slower than the speed of light
• C. slower than the speed of sound
• D. the speed of light
• E. none of the above
The speed of a radio wave is
• A. the speed of sound
• B. slower than the speed of light
• C. slower than the speed of sound
• D. the speed of light
• E. none of the above
The sun
• A. is composed of ionized gas that is mostly
neon
• B. is composed of molecular gas that is mostly
neon
• C. is composed of ionized gas that is mostly
hydrogen
• D. is composed of molecular gas that is
mostly hydrogen
The sun
• A. is composed of ionized gas that is mostly
neon
• B. is composed of molecular gas that is mostly
neon
• C. is composed of ionized gas that is mostly
hydrogen
• D. is composed of molecular gas that is
mostly hydrogen
The energy source for the sun is
• A. combustion of hydrocarbons
• B. solar flares
• C. nuclear fission, the splitting of two
hydrogen atoms
• D. nuclear fusion, the joining of two
hydrogen atoms
• E. combustion of hydrogen
The energy source for the sun is
• A. combustion of hydrocarbons
• B. solar flares
• C. nuclear fission, the splitting of two
hydrogen atoms
• D. nuclear fusion, the joining of two
hydrogen atoms
• E. combustion of hydrogen
The layer of the sun that emits most of the light we see is
• A. the corona
• B. the chromosphere
• C. the photosphere
• D. none of the answers are correct
The layer of the sun that emits most of the light we see is
• A. the corona
• B. the chromosphere
• C. the photosphere
• D. none of the answers are correct
Electromagnetic radiation from astronomical objects can be studied from the surface of the Earth in which part of
the spectrum?
• A. gamma-rays
• B. x-rays
• C. radio
Electromagnetic radiation from astronomical objects can be studied from the surface of the Earth in which part of
the spectrum?
• A. gamma-rays
• B. x-rays
• C. radio
The hotter an object
• A. the brighter it appears at all wavelengths, and the longer the wavelength at which it appears brightest• B. the shorter the wavelength at which it appears brightest• C. The brighter it appears at all wavelengths, and the shorter the wavelength at which it appears brightest• D. the longer the wavelength at which it appears brightest• E. the brighter it appears at all wavelengths
The hotter an object
• A. the brighter it appears at all wavelengths, and the longer the wavelength at which it appears brightest• B. the shorter the wavelength at which it appears brightest• C. The brighter it appears at all wavelengths, and the shorter the wavelength at which it appears brightest• D. the longer the wavelength at which it appears brightest• E. the brighter it appears at all wavelengths
An object emits an emission line spectrum. If the object moves towards
an observer,• A. the observed emission lines shift to
shorter wavelengths
• B. the observed emission lines shift to longer
wavelengths
• C. the emission line spectrum shifts to a
continuous spectrum
• D. the emission line spectrum shifts to
an absorption line spectrum
An object emits an emission line spectrum. If the object moves towards
an observer,• A. the observed emission lines shift to
shorter wavelengths
• B. the observed emission lines shift to longer
wavelengths
• C. the emission line spectrum shifts to a
continuous spectrum
• D. the emission line spectrum shifts to
an absorption line spectrum
The hottest part of the solar atmosphere
• A. found in sunspots
• B. is the photosphere
• C. is the corona
• D. is the chromosphere
The hottest part of the solar atmosphere
• A. found in sunspots
• B. is the photosphere
• C. is the corona
• D. is the chromosphere
Which of the following is ordered by increasing wavelength?
• A. infrared, visible, radio, gamma-ray
• B. visible, infrared, radio, gamma-ray
• C. gamma-ray, visible, infrared, radio
• D. radio, visible, infrared, gamma-ray
Which of the following is ordered by increasing wavelength?
• A. infrared, visible, radio, gamma-ray
• B. visible, infrared, radio, gamma-ray
• C. gamma-ray, visible, infrared, radio
• D. radio, visible, infrared, gamma-ray
An atom is ionized if
• A. it has lost a proton
• B. it has lost an electron
• C. it has lost a neutron
• D. it has absorbed a photon
An atom is ionized if
• A. it has lost a proton
• B. it has lost an electron
• C. it has lost a neutron
• D. it has absorbed a photon
Sunspots appear darker than the surrounding photosphere because
• A. they have a carbonaceous composition
• B. they have an icy composition
• C. they are cooler than their surroundings
• D. they are shadowed from coronal
radiation
Sunspots appear darker than the surrounding photosphere because
• A. they have a carbonaceous composition
• B. they have an icy composition
• C. they are cooler than their surroundings
• D. they are shadowed from coronal
radiation
High mass stars have shorter lifetimes than low mass stars because high mass
stars• A. have luminosities that are far larger than low
mass stars
• B. have less hydrogen than low mass stars
• C. have less helium than low mass stars
• D. release less energy per nuclear reaction
than low mass stars
High mass stars have shorter lifetimes than low mass stars because high mass
stars• A. have luminosities that are far larger than low
mass stars
• B. have less hydrogen than low mass stars
• C. have less helium than low mass stars
• D. release less energy per nuclear reaction
than low mass stars
If the Sun were replaced by a black hole of the same mass,
• A. a great sucking sound would be heard
• B. the Earth would continue to orbit pretty much
as it does now
• C. the Earth would fall directly towards the
black hole
• D. the Earth would spiral into the black hole
over the next 1000 years
If the Sun were replaced by a black hole of the same mass,
• A. a great sucking sound would be heard
• B. the Earth would continue to orbit pretty much
as it does now
• C. the Earth would fall directly towards the
black hole
• D. the Earth would spiral into the black hole
over the next 1000 years
The most common stars are
• A. lower main sequence stars
• B. supergiants
• C. giants
• D. upper main sequence stars
• E. neutron stars
The most common stars are
• A. lower main sequence stars
• B. supergiants
• C. giants
• D. upper main sequence stars
• E. neutron stars
Main sequence stars
• A. are stars which have no hydrogen or
helium
• B. have nuclear fusion of hydrogen
occurring in their cores
• C. are stars which are mostly made of
hydrogen
• D. are stars found in spiral arms
Main sequence stars
• A. are stars which have no hydrogen or
helium
• B. have nuclear fusion of hydrogen
occurring in their cores
• C. are stars which are mostly made of
hydrogen
• D. are stars found in spiral arms
A planetary nebula is
• A. produced by a supernova explosion
• B. a nebula within which planets are
forming
• C. the expelled outer envelope of a
medium mass star
• D. a cloud of hot gas surrounding a planet
A planetary nebula is
• A. produced by a supernova explosion
• B. a nebula within which planets are
forming
• C. the expelled outer envelope of a
medium mass star
• D. a cloud of hot gas surrounding a planet
The density of a __________ is greater than the density of a ___________.
• A. neutron star, black hole
• B. pulsar, neutron star
• C. pulsar, white dwarf
• D. white dwarf, pulsar
• E. white dwarf, black hole
The density of a __________ is greater than the density of a ___________.
• A. neutron star, black hole
• B. pulsar, neutron star
• C. pulsar, white dwarf
• D. white dwarf, pulsar
• E. white dwarf, black hole