1 Light What is light? 1. How does light behave? 2. What produces light? 3. What type of light is emitted? 4. What information do you get from that light?
2 Methods in Astronomy Photometry Measure total amount of light within a certain filter Study distribution and extent of object Spectroscopy Slit up light into its wavelength components Study particular absorption and emission lines Need to understand astrophysical radiation processes Understand some of the relevant physics Be able to interpret the measured light information
3 Today s Overview and Concepts 1) What is Light? Properties? 2) Analyze Black Body Radiation and understand correlations between: color dominant wavelength surface temperature flux luminosity magnitude radius 2) How can you determine those properties of stars? 3) The Hertzsprung-Russel Diagram
4 Electromagnetic Radiation Newton: Beam of light separated into rainbow colors
5 The spectrum has a much wider range; ranging from Gamma to Radio Waves The "visual" part is only a small fraction of the entire electromagnetic spectrum. Visual: 4000 to 7000 Å (1 Å = m) This is also in your toolkit.
8 Infra-Red Radiation night animals
9 How do Waves behave? Ocean Waves Interference Pattern Does light also show an Interference Pattern??
10 How do we know that light is wave? It behaves like waves What happens when two waves are interfering?
11 Demo of Joung s Double Slit Experiment
13 Medium? ---- Ether? Light waves in what?? Light is electromagnetic radiation. What is that? It is a self-perpetuation wave, where the electric field gives rise to a magnetic field which in turn gives rise to an electric field What is propagating? Space around an electric charge may be characterized by an electric field, E, which manifests itself as a force on a test charge placed nearby. If an electromagnetic wave encounters such a test charge, that charge will oscillate. Maxwell s equations say that a time varying electric field produced a perpendicular time-varying magnetic field B. This disturbance in B then gives rise to a time varying E, which in turn this therefore is a self-propagating wave of electric and magnetic fields in a vacuum.
14 Waves Wavelength is the distance from crest to crest Frequency is the number of crests passing per second Velocity of light is 300,000 km/sec h = h o sin 2πx λ c = λ ν How do we know that light is wave? It behaves like waves
15 Light Waves E B = = E B o o 2π sin λ 2π sin λ ( x ct) ( y ct) Light is electromagnetic radiation. It is a self-perpetuation disturbance, where the electric field gives rise to a magnetic field which in turn gives rise to an electric field
16 But.. How do you get shadows with waves??? How do you get photos? (do waves make photos?) Is light a particle?
17 The Photoelectric Effect Light is a Particle called "Photon"
18 The Photoelectric Effect In 1905 Einstein made 4 main discoveries: Brownian motion Photo-electric effect Special Relativity E=mc 2 He got the Nobel prize for the Photo-Electric Effect.
19 Einstein showed that: light is a particle, called "Photon" light is quantized (more later) the energy of a photon is related to the frequency of light E = hν Energy frequency
20 Relationship between the velocity of light, its wavelength and its frequency is: c = λ ν ν E = h = h c λ More Energy Frequency of light = ν Wavelength of light = λ Energy of light = E Planck s constant = h Speed of light = c Shorter Wavelength Faster rate of waves passing
21 Paradox? Can Proof that Light is a Wave Can Proof that Light is a Particle Which is correct? A Particle with a Wavelength??? (What type of animal is that?)
22 Paradox? The experiment shows that light has a wave character The experiment shows that light has a particle character Which statement is correct? We determine reality by experimenting. The experiment itself determines reality. The experiments give contradictory results How, then, do we know what is really true in Life?
23 Energy and Intensity of Light E = hν = h c λ
24 What produces light? hot bodies Today: Experiment & Theory hot gases Today: Experiment only shocks and friction electric fields magnetic fields chemical reactions nuclear reactions
25 The Light Bulb Radiation from a dense body, i.e., from the Iron Wire inside the bulb To be compared later to the and
26 What is a Black Body? A Perfect Absorber no Reflection Perfect Emitter Def: A black body is an object that absorbs ALL radiation that is incident upon it. this makes it black
27 The Spectrum of a Light bulb Red light disappears Less light More light Less light Blue light disappears
28 The Black Body Spectrum Less light Most light Black Bodies emit Light with a characteristic Spectrum This shape is meant by that Less light Blue light disappears Red light disappears
29 The Black Body Spectrum Black Bodies emit Light with a characteristic Spectrum Empirical formula = = kt h kt hc e c h I e hc I ν ν λ λ ν λ
30 The Light-bulb experiment Decrease electricity supply total amount of light decreases color gets redder (relatively less blue light) temperature gets colder Have a relationship between: Color, Temperature & Brightness
33 Experimental Findings for Black Body 1) Hotter Bodies emit more light Temp 4 Flux This is Stefan-Bolzman s law F = σ T 4 2) Hotter bodies emit bluer light Temp 1/wavelength This is Wien s law λ max = T
34 Graphical Illustration Hotter bodies emit bluer light Temp 1/wavelength [Inverse relationship] This is Wien s law λ max = T
35 Total Flux Total energy density radiated at all wavelengths Area under the curve Integrate over all wavelengths Flux = 0 F( λ) dλ
36 T F e x dx from Tables Integral T e x dx c h k hc kt x Substitute hc kt e hc kt hc kt d hc hc kt by Multiply e d hc d F F Integrate e hc F x x kt hc kt hc kt hc σ π λ λ λ λ λ λ λ λ λ λ λ λ = = = = = = = =
37 Stars have colors
38 HST image of Quintuplet Cluster - almost real colors
39 Stars are roughly black bodies
40 Do not see this light
41 Bolometric correction λ λ = A A V d F L ) ( Since know the shape of the a Black Body Curve know how much light missing Apply so-called bolometric correction V A A Bol m d F d F m L L m m + = = ) ( ) ( 2.5log 2.5log λ λ λ λ
42 Determining the Temperature Method 1: By Eye Figure out the colors; Get λ max ; Use Wien s law to get temperature. How do you determine the dominant wavelength? Betelgeuse: color red λ max Rigel: color blue λ max
43 Rigel: λ max is around 4000Å this is in the blue part of the spectrum Betelgeuse: λ max is around 7000Å this is in the red part of the spectrum.
44 Which star is hotter? By how much? Betelgeuse: color red λ max = 7000Å Rigel: color blueish λ max = 4000Å Recall Wien's law: T = λ max But watch out for UNITS Temperature has to be in Kelvin Wavelength in meters (e.g. 7000Å = 7000 x m = 7 x 10-7 m)
45 Temperature scale Absolute Zero In Astronomy we always use the Kelvin Scale. Why? Absolute Zero corresponds to Zero Energy
46 Recall Wien's law: T = λ max First convert units: Betelgeuse: color red λ max = 7000Å = 7 x 10-7 m Rigel: color blueish λ max = 4000Å = 4 x 10-7 m Betelgeuse Rigel TB = = 4000K m ( λ ) max ( λ ) B TR = = 7000K m max R Calculation easier in ratios T T B R ( λ ) ( λ ) o ( λmax ) R 4000 A 4 = = ( λ ) 7 max B = = o max B max R 7000 A Betelgeuse is 4/7 times as hot as Rigel
47 Quiz Question 1: Hot Human Bodies Temperature? About 37 o Celsius = 310 Kelvin λ 0 6 max = = = T K m λ λ max max = meters = 9.4 micro meters Humans emit at ~ 9µm Humans emit light at INFRA RED wavelengths
48 Quiz Question 2: Ice & Cold Dust Temperature? About 0 o Celsius = 273 Kelvin λ 0 6 max = = = T λ λ max max K = meters = 10.4 micro meters m Ice emit light at near INFRA RED wavelengths Dust has temp of ~ K And thus emits at ~ µm Which is at near to far IR wavelengths
49 Other objects
50 Filters & Experiments with Pictures (Photometry Lab) Determining the "color index Quantitative Method a) Measure the magnitudes using filters, e.g., B & V b) Determine the color index (B-V) c) Then use Wien s law to get Temperature
51 First Look at the Spectra of Stars Then look at the entire Electromagnetic Spectrum in your Toolkit The Visual Part of the Spectrum is marked in the picture below Spectrum (a): We see relatively more red light Spectrum (c): We see relatively more blue light Correlating Colors and Dominant Wavelengths Spectrum (a): Dominant Wavelength is at Long Wavelengths here in the IR Spectrum (c): Dominant Wavelength is at Short Wavelengths here in the UV Red yellow λ max in IR λ max in Visual blue λ max in UV
52 How do your "measure" colors? Use filters, take black and white pictures (not color), then measure magnitude in each filter
53 HST image of Quintuplet Cluster -- almost real colors
54 Horsehead Nebula
55 Nebulosity in Sagittarius
56 How do your "measure" colors? Use filters & take (black and white ) pictures, then measure magnitude in each filter; Then calculate the Difference in Magnitude in two Filter Bands.
57 Blue star: much light in blue filter relatively less light in red filter Red star: less red light than blue star but relatively more light in red filter than blue star
58 Color = λ λ λ λ λ λ d R Flux d R Flux V B B V ) ( ) ( ) ( ) ( 2.5log T V B = 0 + Color index = B-V = Magnitude in B Magnitude in V Empirical relationship for solar like stars:
59 The Hertzsprung Russel Diagram For all stars can determine their absolute magnitudes and color Make a plot of absolute and color Luminosity M V Temperature B-V
60 The Hertzsprung Russel Diagram For all stars can determine their Luminosities and their Temperatures Make a plot of Stellar Luminosity and Temperature Luminosity M V Temperature or B-V
61 The Hertzsprung Russel Diagram (HRD) Plot of Luminosity and Temperature Most stars are so-called main-sequence stars
62 If both stars have the same color Color and Temperature Wien s law λ max = T Color is the same Temperature is the same Temperature and Flux Stefan-Bolzman s law Flux = σ Temp 4 Temperature is the same Flux is the same
63 Which star is more luminous? Luminosity and Size The Flux the amount of light passing through the green square is the SAME. BIG Star SMALL Star Which star is more luminous? The larger or smaller?
64 Recall Definitions Luminosity: Luminosity is an intrinsic quantity of the star. It is the energy per second emitted from the entire star. This quantity is the flux Units: Watts (or Joules/sec) Flux: The energy per second passing through a certain area. It is the energy per second per square meter. Units: Watts/m 2 (or Joules/sec/m 2 )
65 Luminosity and Size The Luminosity of a star is the total amount of light emitted from its surface. Thus the luminosity is obtained by multiplying the flux by the area of the star. Luminosity = Flux Area
66 Luminosity Luminosity = Flux Area L = F 4πR 2 Recall Stefan-Bolzman's law: F = σ T 4 Insert the value for Flux into the above equation: L = 2 2 4πR F = 4πR σ T 4 L = 2 4πσ R T 4 The Luminosity of a star depends on its Radius and its Temperature
67 Recall: redder stars are cooler Wien s law cooler stars emit less flux Stephan Bolzman s law get more light from bigger stars For Stars: Have a relationship between: Temperature, Luminosity, & Size
68 Determining the Radii of Stars Can figure out radius of a star if know luminosity and temperature. L = 2 4 4πσ R T Aside: In general always compare the stars. Stick to SOLAR units. Why? The sun is a meaningful star for us -- so compare other stars to the sun L L sun = 4πσ 4πσ R 2 4 R T 2 sun T 4 sun = 2 4 R T R 2 sun T 4 sun = R R sun 2 T T sun 4 For easier calculations you can use these L L sun R R sun R = R = sun or L L 2 sun T T T T sun sun 2 4
69 What about the size of a Star? Can you use the small angle formula? size of star = distance angle 206,265" If the angle is measured in arc seconds Angle size of star Distance to the star
70 Example: Betelgeuse Betelgeuse is 100,000 times as luminous as the sun. 5 L Betelgeuse = 10 L Sun Betelgeuse s color is red, the suns, color is yellow. Red color Temp ~ 3000K Yellow colors Temp ~ 6000K Could put the values of the luminosities and temperatures into these formulae: L Sun = 2 4 4πσ RSun TSun L Betel = 2 4 4πσ RBetel TBetel But there is an easier method. Again use ratios.
71 Example: Calculation L Betel L Sun = = 2 4 4πσ RBetel TBetel 2 4 4πσ RSun TSun Procedure (on right): Write down both formulae; Add two lines to turn this into ratios; Cancel constants L L 10 Betel sun 5 R = R R = R Betel sun Betel sun 2 2 T T Betel sun K 6000K K 6000K 10 R R R R R Betel = = = 2 16 Betel Betel sun sun Betel R R = 2 sun = = 1300R = 1300 sun 1 16
72 So Betelgeuse is 1300 times bigger than the sun. How big is that? The Earth Sun distance is 1AU 1300R sun ~ 6AU Betelgeuse is 6 times as big as the Earth Sun distance. Betelgeuse is a Red Supergiant!
73 The Hertzsprung Russel Diagram (HRD) Betelgeuse has a red color (T~3000K) and is very luminous L B =10 5 L sun. This puts Betelgeuse into the top right in the HRD Betelgeuse is much bigger than the sun Big stars are in the top RH Small stars are in the bottom LH
74 BIG Radius increases from bottom left to top right SMALL
75 Mass increases along main sequence from bottom right to top left
76 Frequencies of Stars Most are Main Sequence Stars Smaller Main sequence stars are much more numerous than luminous m.s. stars Next: What are Spectral Types?
77 Summary of Rules: 1) Hotter Bodies emit more light Temp 4 Flux This is Stefan-Bolzman s law F = σ T 4 2) Hotter bodies emit bluer light Temp 1/wavelength This is Wien s law λ max = T 3) Luminosity of a star is light emitted from its surface. Lum Temp 4 and R 2 L = 2 4πσ R T 4
What is light? ight. How does light behave?. What produces light? 3. What type of light is emitted?. What information do you get from that light? Methods in Astronomy Photometry Measure total amount of
Astronomy 114 Summary of Important Concepts #1 1 1 Kepler s Third Law Kepler discovered that the size of a planet s orbit (the semi-major axis of the ellipse) is simply related to sidereal period of the
Electromagnetic Radiation (How we get most of our information about the cosmos) Examples of electromagnetic radiation: Light Infrared Ultraviolet Microwaves AM radio FM radio TV signals Cell phone signals
Lecture 8: Radiation Spectrum The information contained in the light we receive is unaffected by distance The information remains intact so long as the light doesn t run into something along the way Since
Determining the Sizes & Distances of Stars Using the H-R Diagram Activity UCIObs 11 College Level Source: Copyright (2009) by Tammy Smecker-Hane & Michael Hood. Contact firstname.lastname@example.org with questions.
Take away concepts Solar Radiation Emission and Absorption 1. 2. 3. 4. 5. 6. Conservation of energy. Black body radiation principle Emission wavelength and temperature (Wein s Law). Radiation vs. distance
Astro 130, Fall 2011, Homework, Chapter 17, Due Sep 29, 2011 Name: Date: 1. If stellar parallax can be measured to a precision of about 0.01 arcsec using telescopes on Earth to observe stars, to what distance
5. The Nature of Light Light travels in vacuum at 3.0. 10 8 m/s Light is one form of electromagnetic radiation Continuous radiation: Based on temperature Wien s Law & the Stefan-Boltzmann Law Light has
Pressure Lecture 17 : Incandescent lightbulbs How they work Why they are inefficient Lightbulbs How many scientists does it take to change a lightbulb? Undergraduates: None Bright light - hurts... must
Outline MAE 493R/593V- Renewable Energy Devices Solar Energy Electromagnetic wave Solar spectrum Solar global radiation Solar thermal energy Solar thermal collectors Solar thermal power plants Photovoltaics
Using Photometric Data to Derive an HR Diagram for a Star Cluster In In this Activity, we will investigate: 1. How to use photometric data for an open cluster to derive an H-R Diagram for the stars and
LA502 Special Studies Remote Sensing Electromagnetic Radiation (EMR) Dr. Ragab Khalil Department of Landscape Architecture Faculty of Environmental Design King AbdulAziz University Room 103 Overview What
Radiation Transfer in Environmental Science with emphasis on aquatic and vegetation canopy media Autumn 2008 Prof. Emmanuel Boss, Dr. Eyal Rotenberg Introduction Radiation in Environmental sciences Most
How Matter Emits Light: 1. the Blackbody Radiation Announcements n Quiz # 3 will take place on Thursday, October 20 th ; more infos in the link `quizzes of the website: Please, remember to bring a pencil.
II The Nature of Electromagnetic Radiation The Sun s energy has traveled across space as electromagnetic radiation, and that is the form in which it arrives on Earth. It is this radiation that determines
The Nature of Light Light is radiant energy. Travels very fast 300,000 km/sec! Can be described either as a wave or as a particle traveling through space. As a wave A small disturbance in an electric field
Chapter 5 Light and Matter: Reading Messages from the Cosmos Messages Interactions of Light and Matter The interactions determine everything we see, including what we observe in the Universe. What is light?
Investigating electromagnetic radiation Announcements: First midterm is 7:30pm on 2/17/09 Problem solving sessions M3-5 and T3-4,5-6. Homework due at 12:50pm on Wednesday. We are covering Chapter 4 this
The Nature of Light Light and other forms of radiation carry information to us from distance astronomical objects Visible light is a subset of a huge spectrum of electromagnetic radiation Maxwell pioneered
Light bulbs Midterm 2 results Number of people Ave: 31.8/40 Score out of 40 Lecture 17 : Incandescent light bulbs How they work Why they are inefficient Reminders: No HW was due yesterday HW for next week,
Objectives: PS-7.1 Physical Science Study Guide Unit 7 Wave properties and behaviors, electromagnetic spectrum, Doppler Effect Illustrate ways that the energy of waves is transferred by interaction with
Activity 17 Electromagnetic Radiation Why? Electromagnetic radiation, which also is called light, is an amazing phenomenon. It carries energy and has characteristics of both particles and waves. We can
Newton s laws of motion and gravity 1. Every body continues in a state of rest or uniform motion (constant velocity) in a straight line unless acted on by a force. (A deeper statement of this law is that
PHOTOELECTRIC EFFECT AND DUAL NATURE OF MATTER AND RADIATIONS 1. Photons 2. Photoelectric Effect 3. Experimental Set-up to study Photoelectric Effect 4. Effect of Intensity, Frequency, Potential on P.E.
Lecture 7: Light Waves Isaac Newton (1643-1727) was born in the year Galileo died He discovered the Law of Gravitation in 1665 He developed the Laws of Mechanics that govern all motions In order to solve
How is E-M Radiation Produced? 1. Accelerate charged particle back and forth like they do at the radio station. 2. All solids or liquids with temperature above Absolute Zero emit E-M radiation. Absolute
3-1. True or False: Different colors of light are waves with different amplitudes. a.) True b.) False X 3-2. True or False: Different colors of light are waves with different wavelengths. a.) True X b.)
Principles of Imaging Science I (RAD119) Electromagnetic Radiation Energy Definition of energy Ability to do work Physicist s definition of work Work = force x distance Force acting upon object over distance
Astronomy 421 Lecture 8: Stellar Spectra 1 Key concepts: Stellar Spectra The Maxwell-Boltzmann Distribution The Boltzmann Equation The Saha Equation 2 UVBRI system Filter name Effective wavelength (nm)
From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation? From lowest energy to highest energy, which of the following correctly
Light PSC 203 Overview In this section: What is light? What is the EM Spectrum? How is light created? What can we learn from light? In-class activity Discuss your answers in groups of 2 Think of as many
Stars Flux and luminosity Brightness of stars Spectrum of light Temperature and color/spectrum How the eye sees color Which is of these part of the Sun is the coolest? A) Core B) Radiative zone C) Convective
Lecture 4 lackbody radiation. Main Laws. rightness temperature. Objectives: 1. Concepts of a blackbody, thermodynamical equilibrium, and local thermodynamical equilibrium.. Main laws: lackbody emission:
What Are Stars? How are stars formed? Stars are formed from clouds of dust and gas, or nebulas, and go through different stages as they age. star: a large celestial body that is composed of gas and emits
The Greenhouse Effect THE GREENHOUSE EFFECT To understand the greenhouse effect you first need to know a bit about solar radiation what it is, where it comes from and what happens when it reaches Earth.
Light and radiation Light is a type of electromagnetic (EM) radiation, and light has energy. Many kinds of light exist. Ultraviolet (UV) light causes skin to tan or burn. Infrared (IR) light is used in
Name: 1 Introduction Read through this information before proceeding on with the lab. 1.1 Spectral Classification of Stars 1.1.1 Types of Spectra Astronomers are very interested in spectra graphs of intensity
Eksamination in FY2450 Astrophysics Wednesday June 8, 2016 Solutions 1a) Table 1 gives the spectral class and luminosity class of each of the 20 stars. The luminosity class of a star can (at least in principle)
Light and Spectra INTRODUCTION Light and color have intrigued humans since antiquity. In this experiment, you will consider several aspects of light including: a. The visible spectrum of colors (red to
The Electromagnetic Spectrum 1 Look around you. What do you see? You might say "people, desks, and papers." What you really see is light bouncing off people, desks, and papers. You can only see objects
u Chapter 15 Infrared Spectroscopy: Theory An important tool of the organic chemist is Infrared Spectroscopy, or IR. IR spectra are acquired on a special instrument, called an IR spectrometer. IR is used
LIGHT AND ELECTROMAGNETIC RADIATION Light is a Wave Light is a wave motion of radiation energy in space. We can characterize a wave by three numbers: - wavelength - frequency - speed Shown here is precisely
Heat Transfer: Radiation Heat transfer occurs by three mechanisms: conduction, convection, and radiation. We have discussed conduction in the past two lessons. In this lesson, we will discuss radiation.
Some Basic Principles from Astronomy The Big Question One of the most difficult things in every physics class you will ever take is putting what you are learning in context what is this good for? how do
PROJECT 4 THE HERTZSPRUNG RUSSELL DIGRM Objective: The aim is to measure accurately the B and V magnitudes of several stars in the cluster, and plot them on a Colour Magnitude Diagram. The students will
Section 8 All materials, which are above 0 degrees Kelvin (-273 degrees C), emit infrared energy. The infrared energy emitted from the measured object is converted into an electrical signal by the imaging
Earth s Energy Balance & the Greenhouse Effect Outline: The Earth s Energy Balance: Electromagnetic Spectrum: Ultraviolet (UV) Visible Infrared (IR) Blackbody Radiation Albedo (reflectivity) Greenhouse
Chapter 7. Quantum Theory and Atomic Structure A problem arose in Rutherford s nuclear model. A nucleus and electron attract each other; to remain apart the electron must move. The energy of the electron
Adapted from State of Delaware TOE Unit MAKING SENSE OF ENERGY Electromagnetic Waves GOALS: In this Part of the unit you will Learn about electromagnetic waves, how they are grouped, and how each group
Physics 221 Lab 14 Transformers & Atomic Spectra Transformers An application of Inductance The point of a transformer is to increase or decrease the voltage. We will investigate a simple transformer consisting
Name: HR Diagram Student Guide Background Information Work through the background sections on Spectral Classification, Luminosity, and the Hertzsprung-Russell Diagram. Then complete the following questions
Spectra in the Lab Every chemical element has a unique ``signature'' which can be revealed by analyzing the light it gives off. This is done by spreading the light out into a rainbow of color. It may seem
Blackbody radiation derivation of Planck s radiation low 1 Classical theories of Lorentz and Debye: Lorentz (oscillator model): Electrons and ions of matter were treated as a simple harmonic oscillators
Astronomy 110 Homework #04 Assigned: 02/06/2007 Due: 02/13/2007 Name: Directions: Listed below are twenty (20) multiple-choice questions based on the material covered by the lectures this past week. Choose
Chapter 5 Perodicity and Atomic Structure Mendeleev s Periodic Table In the 1869, Dmitri Mendeleev proposed that the properties of the chemical elements repeat at regular intervals when arranged in order
Ch 6: Light and Telescope Wave and Wavelength..\..\aTeach\PhET\wave-on-a-string_en.jar Wavelength, Frequency and Speed Wave and Wavelength A wave is a disturbance that moves through a medium or through
Lecture 2 How does Light Interact with the Environment? Treasure Hunt Find and scan all 11 QR codes Choose one to watch / read in detail Post the key points as a reaction to http://www.scoop.it/t/env202-502-w2
ESCI 107/109 The Atmosphere Lesson 2 Solar and Terrestrial Radiation Reading: Meteorology Today, Chapters 2 and 3 EARTH-SUN GEOMETRY The Earth has an elliptical orbit around the sun The average Earth-Sun
Be Stars By Carla Morton Index 1. Stars 2. Spectral types 3. B Stars 4. Be stars 5. Bibliography How stars are formed Stars are composed of gas Hydrogen is the main component of stars. Stars are formed
OVERVIEW More than ever before, Physics in the Twenty First Century has become an example of international cooperation, particularly in the areas of astronomy and cosmology. Astronomers work in a number
Forensic Spectral Anaylysis: Warm up! The study of triangles has been done since ancient times. Many of the early discoveries about triangles are still used today. We will only be concerned with the "right
Lecture 2: Radiation/Heat in the atmosphere TEMPERATURE is a measure of the internal heat energy of a substance. The molecules that make up all matter are in constant motion. By internal heat energy, we
Quiz Oct 31 2012 Chapter 11 11-1. A nova is believed to occur when which of the following pairs of stars are in a binary system? a) white dwarf, main sequence star X b) white dwarf, neutron star c) neutron
Classroom Exercise ASTR 390 Selected Topics in Astronomy: Astrobiology A Hertzsprung-Russell Potpourri Purpose: 1) To understand the H-R Diagram; 2) To understand how the H-R Diagram can be used to follow
Class: Date: Astro 102 Practice Test 3 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Interstellar gas clouds may collapse to form stars if they a. have
Atomic Emission Spectra Objectives The objectives of this laboratory are as follows: To build and calibrate a simple box spectroscope capable of measuring wavelengths of visible light. To use this spectroscope
Chapter 12 Quiz, Nov. 28, 2012, Astro 162, Section 4 12-1. Where in our Galaxy has a supermassive (or galactic) black hole been observed? a) at the outer edge of the nuclear bulge b) in the nucleus X c)
4.5 Orbits, Tides, and the Acceleration of Gravity Our goals for learning: How do gravity and energy together allow us to understand orbits? How does gravity cause tides? Why do all objects fall at the
Homework #4 Solutions ASTR100: Introduction to Astronomy Fall 2009: Dr. Stacy McGaugh Chapter 5: #50 Hotter Sun: Suppose the surface temperature of the Sun were about 12,000K, rather than 6000K. a. How
Light bulbs Lightbulbs How many scientists does it take to change a lightbulb? Undergraduates: None right light - hurts... must go back to bed. Postgraduates: Funding for a new lightbulb ran out six months
Greenhouse Effect and the Global Energy Balance Energy transmission ( a a refresher) There are three modes of energy transmission to consider. Conduction: the transfer of energy in a substance by means
Polarization and Photon Concept A. Polarization Physics 102 Workshop #8A Name: Lab Partner(s): Instructor: Time of Workshop: General Instructions Workshop exercises are to be carried out in groups of three.