Properties of light
light can be a wave and a particle. they have a wavelength and a frequency.
Photons
particles of light
Electromagnetic spectrum
entire range of wavelengths or light
Wavelength
distance between two adjacent peaks
Frequency
number of times per second a wave vibrates up and down
Speed of light
Frequency x wavelength
Spectrum
a prism split light into the rainbow of light
What we can learn from spectra
chemical composition, surface temp, and how fast an object is moving
Continuous spectra
spectrum of a common light bulb spans all visible wavelengths, without interuption
Emission
a thin or low density cloud of warm gas emits light at specific wavelengths that depend of its composition and temperature producing a spectrum with bright emission lights
Absorption
a cooler gas cloud between us and a light bulb can absorb light of specific wavelengths that depend on cooler gas composition and temperature, leaving dark absorption lines in the spectrum
Transparent
materials that transmit light
Opaque
materials that absorb light
Chemical Fingerprints
every kind of atom, ion and molecule has a unique set of energy levels
Continuous Spectrum
densley packed atoms and molecules cannot be considered independent, so they have much more complex set of energy levels
Thermal spectra
thermal radiation all objects emit it
Stefan- Boltzman Law
hotter objects emit more light at all frequences per unit area
Wilen's Law
hotter objects emit photons with a higher average energy
The doppler shift
tells us how fast an object is moving towards or away from us
Reflection
light can bounce off matter
Radio Waves
longest-wavelength light; form of light not sound
Ultra violet
light with wave lengths somewhat shorter than blue light
Gamma rays
shortest wave length