light and matter

watt

flow of energy per unit time; 1 Joule/second

components of white light

all rainbow colors

photon’s energy depends on

frequency

light has _ fields which oscillate in _

electric and magnetic; opposite directions

what do waves carry and not carry

energy, not matter

atmospheric transmission

some wavelengths are blocked by Earth’s atmosphere, others aren’t

what do transparent and opaque objects do

transmit vs block light

atomic number

number of protons

atomic mass number

number of protons + neutrons

different isotopes have same number of _ but different

protons, neutrons

continuous spectrum

e.g a common lightbulb spanning all visible wavelengths, white noise

emission spectrum

specific wavelength depending on composition and temperature

absorption spectrum

can absorb light of specific wavelengths, leaving dark absorption lines in the spectrum

solid sphere model

Dalton, Greek idea of an indivisible, identical elemental sphere

plum pudding model

Thomson, electrons scattered throughout a sphere of + charge

nuclear model

rutherford, atoms are mostly empty space, with most mass in nucleus and electrons orbiting

planetary model

bohr, orbits have quantized sizes and energies

quantum model

Schrödinger, electrons move in waves instead of set paths, clouds of probability instead of knowing exact location

vibrational and rotational lines

movement of molecules that complicates their spectra, many of which are the infrared range

blackbody spectrum

thermal emission’s continuous spectrum, its peak tells us object’s temperature

thermal radiation

emitted by nearly all large or dense objects, depends on temperature (poker in fireplace getting white-hot

doppler shift

light as well as sound → red and blue-shifting; tells you about the relative motion of distant objects

we measure doppler effect from

shifts in wavelengths of spectral lines; tells us an object’s speed toward or away from us, but only if there’s a component of its motion parallel to our line of sight

doppler shift and rotating objects

different sides of a rotating object spread out its spectral lines, wider when an object rotates faster

doppler broadening in gas

random motions in gas particles caused by a higher temperature broadens the spectral lines

cosmological redshift (not doppler)

light shifts lower in frequency due to Universe’s and the wave’s expansion

velocity of molecule and spectral lines

NO CONTRIBUTION; while it can cause doppler broadening or shifts, it doesn’t create unique spectral lines