Details Title: Chapter 4 Description: chapter 4 Total Flash Cards: 31 Created: 12/06/2008 12:41:24		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Astronomy Flashcards
Cards in this set: Term Heating objects and color Definition As an object heats up, it gets bright, emitting more electromagnetic radiation at all wavelengths   The brightest color (most intense wavelength) of the emitted radiation changes with temperature (red, to orange, to white to blue etc.) Term Blackbody Definition Blackbody-ideal blackbody absorbs all the electromagnetic radiation that strikes it (see colors better than say, if you warmed up a cat :P)   -Incoming radiation heats up blackbody which then reemits the energy it has absorbed, but with different intensities at each wavelength received   Depending on temperature will emit a different color   Colors and types of light emitted by an object determined by their: temperature, density, and composition Term Spectra Definition Three types of spectra: blackbody (continuous), emission line, and absorption line Term Intensity Definition Intensity- measure of how much energy a blackbody emits per second Term A blackbody curve Definition A blackbody curve-depicts in detail the electromagnetic radiation a blackbody emits (emitted entities of blackbody only depend on its surface temperature) Term Wien's law Definition Wien’s law-mathematical relationship between location of peak for each curve and that blackbody’s temperature   -useful for determining temperature of a star   Example: temperature = 3000K and peak = 1000nm; temperature = 6000K and peak = 500nm   High temperatures have peaks at shorter wavelengths Term Stefan-Boltzmann law Definition If you double temperature of an object (say a toaster) from 500 K to 1000K the energy emitted from each square meter increases by factor of 2^4 or 16 times. 500 to 1500 K increased from factor of 3^4 or 81 times   --relates to wavelength, when object is cool it emits infrared and radio photons (very long wavelengths) and when it gets hot it glow mainly in visible spectrum and more of all types of photons (which is why you feel it getting hotter) Term Flux Definition amount of light per square meter of surface being emitted every second   increases rapidly with temperature Term Plancks' law Definition relationship between the energy of a photon and its wavelength   short wavelengths have more energy/ long wavelengths less Term Absorption lines Definition dark lines contained in the solar spectrum by the thousands (light has been absorbed by gases between the sun and the viewer on Earth)   Absorption lines are seen if the background of an object is hotter than the gas between us and it     Term Spectroscopy Definition -process of collecting the spectra of an object Term Spectroscope Definition device that straighten the light rays and magnify the spectrum so that it can be closely examined Term Emission lines Definition bright spectral lines that can be seen through the spectroscope    --Chemists discovered flame consists of emission lines against a dark background and that the number of lines produced (emission) and their colors are unique to the element or compounds that produce them—    -low desnity, hot gas produces bright emission lines   Chemists discovered that the emission lines of a particular gas occur at exactly the same wavelengths as the absorption lines of that gas --use this to figure out what stars are made of since each element has unique lines   Emission lines are seen if the back-ground is cooler than such a gas       Term Spectral analysis Definition the identification of chemical substances by their spectral light Term Element Definition fundamental substance that cannot be broken down into more basic units and still retains its properties Term Spectrograph Definition device for photographing a spectrum Term Diffraction grating Definition piece of glass on which thousands of closely spaced parallel groves are cut (used in spectrographs today) Term Kirchoff's law Definition Law 1: a solid, liquid, or dense gas produce a continuous spectrum (continuum)-a complete rainbow of colors without any spectral lines (light emitted at all wavelengths, amount depends upon object’s temperature)   Law 2: rarefied (opposite of dense) gas produces an emission line spectrum—a series of bright spectral lines against a dark background (example of this are neon lights)   Law 3: Light from an object with a continuous spectrum that passes through a cool gas produces an absorption line spectrum-a series of dark spectral lines among the colors of the rainbow (sunlight and light from stars which pass through cooler gases to reach Earth) Term Continuum (Continuous/Black body) Definition Continuum is seen if there is no gas between an object and the observer   -all colors Term Radioactive Definition -overtime element naturally and spontaneously transforms into another element by emitting particles Term Nucleus Definition dense “something” in middle, composed of protons and neutrons Term Strong Nuclear force Definition -Force of the neutrons in the middle of an atom strong enough to keep the protons and electrons, which are repelling like particles (protons repel protons etc.) “glued” together Term atomic number Definition