what i did for spring break …. bit of administration …. readingreading –bsnv chaps. 7 and 8...

What I did for Spring Break …What I did for Spring Break …

Bit of Administration ….Bit of Administration ….• ReadingReading

– BSNV Chaps. 7 and 8 BSNV Chaps. 7 and 8

• Particularly important discussion section - Particularly important discussion section - don’t miss this weekdon’t miss this week

• Additional observations for Lab 2, through April 5Additional observations for Lab 2, through April 5

• Washburn Observatory - 7 - 9 Monday, TuesdayWashburn Observatory - 7 - 9 Monday, Tuesday– Drop in for Venus, Mars, Saturn, Jupiter, Orion …Drop in for Venus, Mars, Saturn, Jupiter, Orion …

• Honors - 4:30 this afternoon, Astronomy LibraryHonors - 4:30 this afternoon, Astronomy Library

The Physics of LightThe Physics of Light

• Spectroscopy and Atomic PhysicsSpectroscopy and Atomic Physics

• Types of SpectraTypes of Spectra

Continuous - No spectral linesContinuous - No spectral lines

Absorption - Dark lines superimposed on continuous spectrumAbsorption - Dark lines superimposed on continuous spectrum

Emission - Isolated bright linesEmission - Isolated bright lines

The Physics of LightThe Physics of Light• Spectroscopy and Atomic PhysicsSpectroscopy and Atomic Physics

• Graphical SpectraGraphical SpectraIn

tens

ity


• Kirchoff’s LawsKirchoff’s Laws

The Physics of LightThe Physics of Light• SpectroscopySpectroscopy

• Thermal RadiationThermal Radiation


• Thermal RadiationThermal Radiation• Wien LawWien Law

€

λmax = 3x106

T

λmax in nmT in oK

λλmaxmax


• Thermal RadiationThermal Radiation• Wien LawWien Law• Stefan-Boltzmann LawStefan-Boltzmann Law

€

E flux =σT 4

Stefan-Boltzmann constant

fluxflux energy emitted energy emitted from square meterfrom square meter in one second in one second


• Quantum Mechanics - Electron can only be in certain specificQuantum Mechanics - Electron can only be in certain specific orbits <=> can only have certain specific energiesorbits <=> can only have certain specific energies

QuantumQuantumNumbersNumberse

HydrogenHydrogenAtomAtom


• Quantum Mechanics - Electron energy changes can only haveQuantum Mechanics - Electron energy changes can only have certain values corresponding to energy changes between orbitscertain values corresponding to energy changes between orbits ==> only certain energies of photons can be absorbed or emitted ==> only certain energies of photons can be absorbed or emitted


• Shine “white” light onto hydrogen atom; for simplicity, considerShine “white” light onto hydrogen atom; for simplicity, consider all electrons to be in level 2 (highly unrealistic!)all electrons to be in level 2 (highly unrealistic!)

Wavelength

Phot

ons/

sec

White lightWhite light


• Only photons with energy equal to energy differenceOnly photons with energy equal to energy difference between orbits 2 and 3 are absorbed. This energybetween orbits 2 and 3 are absorbed. This energy corresponds to a wavelength of 660 nm.corresponds to a wavelength of 660 nm.

Wavelength

Phot

ons/

sec

660 nm


• Photons with energy equal to energy differencePhotons with energy equal to energy difference between orbits 2 and 3 are emitted. These photonsbetween orbits 2 and 3 are emitted. These photons are emitted in all directions.are emitted in all directions.

Wavelength

Phot

ons/

sec

660 nm


• Energy Level DiagramsEnergy Level Diagrams

Ground State

Ener

gy

The circled arrows (“electron transitions”) represent The circled arrows (“electron transitions”) represent

A) emission linesA) emission lines B) continuous emissionB) continuous emission C) absorption linesC) absorption lines

ConcepTest!ConcepTest!

You would expect these emission lines to be found in what part of You would expect these emission lines to be found in what part of the electromagnetic spectrum? the electromagnetic spectrum?

A) UltravioletA) Ultraviolet B) OpticalB) Optical C) InfraredC) Infrared D) RadioD) Radio

ConcepTest!ConcepTest!

The Physics of LightThe Physics of Light

• Hydrogen SpectrumHydrogen Spectrum

BalmerSeries

Lyman Series

Wavelength (nm)

Infrared Optical Ultraviolet

TelescopesTelescopes• Fundamental Purpose - To Collect LightFundamental Purpose - To Collect Light

Light from a StarLight from a Star

Faint Bright Brightest

TelescopesTelescopes• Fundamental Purpose - To Collect LightFundamental Purpose - To Collect Light

1 cm

5 cm

10 cm

Collecting Area = R2 = * 1 cm2



“ 0.2m Telescope ”

TelescopesTelescopes• DesignDesign

Focu

s(I

mag

e)

LightDetector Refractor

ObjectiveLens

TelescopesTelescopes•ExamplesExamples

40” RefractorYerkes ObservatoryWilliams Bay, WI

TelescopesTelescopes• DesignDesign

Focu

s(I

mag

e)Light

Detector

LightDetector Refractor

ObjectiveLens

Reflector

ObjectiveMirror

TelescopesTelescopes•Light Detectors - Charge-Coupled Devices (CCDs)Light Detectors - Charge-Coupled Devices (CCDs)

TelescopesTelescopes•ExamplesExamples

TelescopesTelescopes• Electromagnetic Electromagnetic SpectrumSpectrum

TelescopesTelescopes

•Beyond Visible LightBeyond Visible Light

TelescopesTelescopes

•Telescopes in SpaceTelescopes in Space

TelescopesTelescopes•Telescopes in SpaceTelescopes in Space

OpticalInfrared

Optical

X-ray

CrabNebula

Tucson 1975 Tucson 1995

what i did for spring break …. bit of administration …. readingreading –bsnv chaps. 7 and 8...

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