Astro 11
Terms
undefined, object
copy deck
- temperature
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=energy of motion of atoms/molecules of an object
absolute zero=temp at which all motion ceases. (0 K, -273 C, -459 F) - wavelegnth
- legnth over which wave repeats in pattern (meters)
- frequency
- how often the wave repeats itself (cycles per second)
- speed=
- wavelegnth times frequency
- electromagnetic spectrum
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radio, infrared, visible, ultraviolet, x-ray, gamma ray
(left to right) frequency increases, wavelegnth decreases - the hotter the object..
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-> higher temp -> faster the particles move -> more energy they radiate
(more intensely it radiates energy) - blackbody curve
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=distribution of reemitted radiation; in steady state, (when T is contant), blackbody must reemit same amount of energy it absorbs
curve shifts toward higher frequencies (shorter wavelegnths) and greater intensities as the object's temp increases - stefan-boltzmann law
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intensity of light is directly related to temp of the object to the fourth power
intensity= T^4 - wien's law
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wavelegnth of peak emission= 1/T
the hotter an object, the bluer its radiation/ the shorter its wavelegnth - continuous spectra
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covers full range of wavelegnths
rainbow running from red to violet w/out interruption. - emission spectra
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pattern of spectral emission lines that represent emission at only certain wavelengths
hot,low density gas - absorption spectra
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certain wavelegnths missing; dar lines in otherwise continuous bright spectrum, where light w/in 1 narrow frequency range has been removed
cool, low density gas - model of atom
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nucleus=core
protons=positive; # determines what element it is
neutrons=neutral; # determines what isotope the element is
electrons=negative; orbit the nucleus - why movement of electrons around nucleus cause atom to absorb/emit enegery?
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1.opposites attract
2.discrete levels; different electrons have different allowed electron levels. closest are in ground state
3.discrete energy levels
4.when electron absorbs enough energy, can pull away- ion - energy levels
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if low energy photon strikes electron, it is absorbed and electron jumps up 1 level
higher energy photon will cause electron to jump 2 levels
higher energy of photon=higher jump
electron in higher levels= excited (but wants to go back into ground state) - hydrogen spectra
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hydrogen= most abundant element in universe; simplest atom
lyman series:91-122 nm (UV)
balmer series:365-656 nm (visible and UV)
paschen series:820-1875 nm (IR) - doppler effect
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observer in front of source: shorter wavelegnths, blueshifted
observer in back of source: longer wavelegnths, redshifted - blueshift/redshift
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blueshift: shift towards blue (shorter wavelegnths)due to object moving towards us
redshift: shift towards red end of spectrum (longer wavelengths)