Astronomy Chapter 2:

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Electromagnetic Radiation
Another term for light, transfers energy and information from one to another
Visible Light
Small range of the electromagnetic spectrum that human eyes perceive as light
Region of the electromagnetic spectrum corresponding to radiation of the longest wavelengths
Region of the electromagnetic spectrum just outside the visible range, corresponding to light of a slightly longer wavelength than red light
Region of the electromagnetic spectrum, just beyond the visible range, corresponding to wavelengths slightly shorter than blue light
Region of the electromagnetic spectrum corresponding to radiation of high frequency and short wavelength, far beyond the visible spectrum
Gamma Rays
Region of the electromagnetic spectrum far beyond the visible spectrum, corresponding to radiation of very high frequency and very short wavelength
Pattern that repeats itself in both time and space, characterized by the speed at which they move, their frequency, and their wave length
Wave Period
Amount of time required for a wave to repeat itself at a specific point in space
The distance from one wave crest to the next at a given instant in time
The maximum deviation of a wave above or below zero point
The number of wave crests passing any given point per unit time
Waves ability to bend around corners, diffraction of light establishes its wave nature
Ability of two or more waves to interact in such a way that either reinforce or cancel each other
Elementary particle with a negative charge
Elementary particle with a positive charge
Electric Field
A field extending outward in all directions from a charged particle, such as a proton or an electron
Magnetic Field
Field that accompanies any changing electric field and governs the influence of magnetized objects on one another
The union of electricity and magnetism which do no exist as independent quantities but are in reality two aspects of a single physical phenomenon
Speed of Light
Fastest possible speed
Electromagnetic Spectrum
The complete range of electromagnetic radiation, from radio waves to gamma rays including a visible spectrum
A quantity that measures a material’s ability to block electromagnetic radiation, opposite of transparency
A measure of the amount of heat in an object and an indication of the speed of the particles that comprise it
A basic property of electromagnetic radiation that specifies the amount of strength of the radiation
Blackbody Curve
The characteristic way in which the intensity of radiation emitted by a hot object depends on frequency
Wien’s Law
Relation between wavelength at which a blackbody curve peaks and the temperature of the emitter. Wavelength proportional to temperate, so hotter the object, bluer its radiation
Stefan’s Law
Relation that gives the total energy emitted per square centimeter of its surface per second by an object of a given temperature
An instrument used to view a light source so that it is split into its component colors
Continuous Spectra
Spectra in which the radiation is distributed over all frequencies
Emission Lines
Bright line in a specific location of the spectrum of radiating material, corresponding to emission of light at a certain frequency
Emission Spectrum
The pattern of spectral emission lines produced by an element
Absorption Line
A dark line in a bright spectrum, where light within one narrow frequency range has been removed
The study of the way in which atoms absorb and emit electromagnetic radiation
Kirchoff’s Laws
Three runs governing the formation of different types of spectra
Building block of matter, made up of protons, electrons, and neutrons
Dense, central region of an atom containing both protons and neutrons and orbits by one or more electrons
Bohr Model
First theory of the hydrogen atom to explain the observed spectral lines. Three ideas: State of lowest energy for the electron that there is a maximum energy beyond which the electron is no longer bound to the nucleus, and that within these two energies the electron can only exist in certain energy levels
Ground State
The lowest energy state that an electron can have within an atom
Excited State
State of an atom when one of its electrons is in a higher energy orbital than the ground state. Atoms can become excited by absorbing a photon of a specific energy or by colliding with a nearby atom
Individual packet of an electromagnetic energy that makes up electromagnetic radiation
Matter made up on particular atom, the number of protons with the nucleus of the atom determines which element it represents
An elementary particle with roughly the same mass as a proton, but which is electrically neutral
A tightly bound collection of atoms held together by the atoms’ electromagnetic fields. Molecules, like atoms, emit and absorb photons at a specific wavelength
Doppler Effect
Any motion-indued change in the observed wavelength (or frequency) of a wave
Categories: Astronomy