second midterm notes

7 Pages
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Department
Astronomy & Astrophysics
Course Code
AST101H1
Professor
Clifford Orwin

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Description
Ch.5 White light-mixture of basic colored light in equal proportions. Black=no light, no color Emission-eg.light bulb,energy of light comes fr electricity potential energy. Absorption-eg.cover light bulb w hand,hand absorbs some light&this energy makes hands warm. Transmission-eg.glass,air allows light to pass through. Reflectionscattering-light bounce off matter,reflection-same direction. Scattering-random direction wave-wavelength, frequency, period.c=f*wavelength, Particles-thing Wave-pattern revealed by p. Light-Electromagnetic waveconsists of individual photons characterized by wavelength,frequency& energy.Speed is constant.-both wave&particles. Electomagnetic spectrum-Gamma rays-Xrays-ultraviolet-visible-infrared-radio. Atoms-protons, neutrons,electrons,nucleus. Atom#=proton# Atomic mass#=#of protons=#neutrons Isotope-elements w different# of neutrons. Atoms-molecules-compounds Phases-solid,liquid,ice.-Chemical bonds stronger-tighter-sold , if weaker, then liquid, gas -eg. Water- Sublimation-escape solid Evaporation-escape liquid -Molecular dissociation-high temp->molecule collide->break bonds->lose electrons->ionized -Plasma-type of gas which atoms have become ionized. eg. Sun is made of plasmahot gas Pressure-force per unit area. Earth core is solid cuz of pressure, tho its temperature is high. Energy level transition-as electron rise fr low energy level to higher onefall fr high to low. Spectroscopy-obtain spectrum&read info.display graphs showing intensity at diff. Wavelengths. -Continuous spectrum-broad range of wavelengths wout interruption. -Emission line spectrum-low density clouds emits light only at specific wavelengths. Depends on composition&temperature. Emission lines against a black background. -atoms in cloud collide bump electrons to high energy level,then fall back &loses energy by emitting photon of light at specific wavelength. -Absorption line spectrum-cloud lies bw source&us, still see most continuous light,cloud absorbs some at specific wavelengths. Dark absorption lines over rainbow. -as atoms absorb light,electon fr high leve return to low level&emits a photon of same energy absorbed but goes to random directions. Chemical Fingerprint-elements emitsabsorb light at diff wavelength, by observing spectrum,unique patterns can determine wat element. Ions cud help determine temp.->high temp-more highly charged ions. Molecules-create spectral lines wen electron change energy levelvibrationrotation.Tightly brunched lines-molecular band Thermal Radiation-atoms&molecules in objects r not independent, have complex energy levels-> absorb light across broad range of wavelengths.as absorb photons,photons try to escape, its quickly absorbed by atommolecule->reemits photon at diff wavelen. &direction->photons bounces randomly->constantly exchange energy->when it finally escapes,the radioactive energies spread over wide range of wavelengths ->produce continuous spectrum--Only depends on temperature->rep.avg.kinetic e. -Two laws-1.Each square metre of hotter objects surface emits more light at all wavelength. 2.Hotter objects emit photons w higher avg. energy (shorter avg. wavelengths) -estimate stars temp. by observing its color. Eg.ppl-infrared star-red-3000k. -reflected light gives color, absorbed light heat the surface &help determine temp. Doppler effect-Blue shift-Object move toward us,waves bunch up bw us&object,shorter wavelengh -Red shift-object move away fr us,light is shifted to longer wavelength. Only when object is moving directly away fr. Us we know full speed. Ch.7 Comparative planetology-compare to one another,find similaritiesdifferences. Sun-helium+hydrogen. Sun spots are cooler areas. Solar storms->send streamers of hot gas above surface. Loses 4 million tons of masssec,will shine for another 5 billion yrs. Mercury-Smallest among eight.-not active, no wind. Both hot and cold extremes. Heavily cratered. www.notesolution.com
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