Astronomy

Light as Evidence flashcards

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What is meant by “Electromagnetic radiation” in this lesson?Electromagnetic Radiation
Electromagnetic radiation carries energy through waves and photons across a range of wavelengths.
What is meant by “Wavelength” in this lesson?Electromagnetic Radiation
Wavelength is the spatial interval between corresponding points in a wave.
What is meant by “Frequency” in this lesson?Electromagnetic Radiation
Frequency is the number of wave cycles per unit time.
What is meant by “Photon energy” in this lesson?Electromagnetic Radiation
Photon energy is proportional to frequency.
What is meant by “Electromagnetic spectrum” in this lesson?Electromagnetic Radiation
The spectrum ranges from radio through gamma radiation.
What is meant by “Thermal spectrum” in this lesson?Electromagnetic Radiation
A thermal spectrum's distribution relates to emitter temperature under the relevant approximation.
What is meant by “Emission line” in this lesson?Spectroscopy and Motion
An emission line is enhanced radiation at a wavelength associated with a transition.
What is meant by “Absorption line” in this lesson?Spectroscopy and Motion
An absorption line reduces intensity at a wavelength where material absorbs radiation.
What is meant by “Spectral identification” in this lesson?Spectroscopy and Motion
Identification compares measured patterns with known atomic or molecular transitions.
What is meant by “Doppler shift” in this lesson?Spectroscopy and Motion
A Doppler shift changes observed wavelength through relative motion along the line of sight.
What is meant by “Radial velocity” in this lesson?Spectroscopy and Motion
Radial velocity is velocity along the observer's line of sight.
What is meant by “Spectral limitation” in this lesson?Spectroscopy and Motion
A limitation describes ambiguities and conditions affecting interpretation.
What is meant by “Luminosity” in this lesson?Luminosity, Flux, and Brightness
Luminosity is total emitted energy per unit time.
What is meant by “Flux” in this lesson?Luminosity, Flux, and Brightness
Flux is received energy per unit area per unit time under the stated measurement.
What is meant by “Inverse-square relation” in this lesson?Luminosity, Flux, and Brightness
For an unobscured isotropic source in the simple geometry, flux decreases with distance squared.
What is meant by “Apparent magnitude” in this lesson?Luminosity, Flux, and Brightness
Apparent magnitude is a logarithmic brightness measure with lower values indicating greater brightness.
What is meant by “Absolute magnitude” in this lesson?Luminosity, Flux, and Brightness
Absolute magnitude describes the magnitude at a defined reference distance and band.
What is meant by “Extinction” in this lesson?Luminosity, Flux, and Brightness
Extinction dims radiation through absorption or scattering by intervening material.