Presentation on theme: "Exam 1 Next Tuesday Covers chapters 1, 2, S1, 4, 5 and 6 2 essay questions/25 multiple choice Allowed one standard sized sheet of notes, writing on one."— Presentation transcript:
Exam 1 Next Tuesday Covers chapters 1, 2, S1, 4, 5 and 6 2 essay questions/25 multiple choice Allowed one standard sized sheet of notes, writing on one side only.
Explain how Newton came up with his law of gravity Explain tidal forces Explain what light is, how it is created Explain why wave speed, frequency, wavelength and energy are related Explain the properties of thermal/blackbody radiation Explain line absorption/emission from atoms and molecules
Discussion If the leaf is moving toward the source of the water waves, will the frequency be greater or less than when the leaf was still?
Red/blueshift Redshift – if we are moving away from a light source, the frequency of spectral lines will be shifted slightly lower, toward the red end of the spectrum. Blueshift – if we are moving toward a light source, the frequency of spectral lines will be shifted slightly higher, toward the blue end of the spectrum.
Important points 1.The light does not necessarily appear red or blue. You can have a red spectral line which is blueshifted, or a blue line which is redshifted. 2.The Doppler effect depends on your relative velocity toward or away from an object, not on your distance from it.
Radial velocity By measuring the wavelength of spectral lines in a star or galaxy and comparing it to the lines produced by lamps, we can determine the velocity of stars and galaxies either toward or away from us.
Proper motion The “proper” motion of a star is the motion relative to other stars in the plane of the sky. In general one has to wait many years to determine the proper motion of even the closest stars. We can’t measure the proper motion of galaxies, because they are too far away.
Explain how continuous spectrum and line spectra are created, physically and practically explain scattering and reflection explain the Doppler effect explain how lenses bend light how astronomers use telescopes and the effects of the atmosphere