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.)

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

Three types of spectra: blackbody (continuous), emission line, and absorption line

Intensity- measure of how much energy a blackbody emits per second

A blackbody curve-depicts in detail the electromagnetic radiation a blackbody emits (emitted entities of blackbody only depend on its surface temperature)

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

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)

amount of light per square meter of surface being emitted every second

increases rapidly with temperature

relationship between the energy of a photon and its wavelength

short wavelengths have more energy/ long wavelengths less

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

device that straighten the light rays and magnify the spectrum so that it can be closely examined

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

the identification of chemical substances by their spectral light

fundamental substance that cannot be broken down into more basic units and still retains its properties

piece of glass on which thousands of closely spaced parallel groves are cut (used in spectrographs today)

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)

Continuum is seen if there is no gas between an object and the observer

-all colors

dense “something” in middle, composed of protons and neutrons

different combinations of protons and neutrons

-some isotopes are stable, but most are not and come apart spontaneously this produces the radioactive isotope

-use this to age space rock and debris etc.

when an atom contains a different number of electrons than protons

when atoms share electros and become bound together

Each molecule has a different set of allowed electron orbits with energies associated with each orbit—electrons must stay within orbit unless making a transition

electron in orbit with more energy than the lowest energy state available to it

To move up energy levels electrons must absorb photons—but they can only absorb photons that contain the precise amount of energy needed to jump to the next energy level otherwise the photon passes through the atom (energy== certain wavelength)

Absorption lines –caused by photons taken out of the stream of light by electrons, which then move to higher energy levels

Electrons are unstable in higher energy levels-often nudged back down by bumping into other particles or virtual particles –when it does this it emits a photon with energy equal to the distance it must go down (absorbed photon has same wavelength as emitted photon)

--same wavelengths but emitted photon sent out in all directions causing the gas to glow (color depends on type of gas)

determined by measuring a star’s motion relative to background stars