Midterm__2_Study_Guide - Astronomy Study Guide Chapter 4.8...

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Astronomy Study Guide Chapter 4.8 Tidal Forces are differences in the gravitational pull at different points on an object. They reveal how gravitational can pull objects apart rather than drawing them together. The tidal forces of the Moon and Sun produce tides in the Earth’s oceans The tidal forces on the Earth have locked the Moon into synchronic rotation Spring tides – large shifts in water levels that occur when sun, earth and the moon line up Neap tides – first and last quarter when the moon and the sun form a right triangle to the earth, the tidal effects cancel each other out. Chapter 5 Prediction of the electromagnetic waves by Maxwell – By combining his four equations Maxwell showed that electric and magnetic fields should travel through space in the form of waves at the speed of 3.00 * 10^5 km/s – a value exactly equal to the best available value of speed of light. Maxwell’s suggestion that these wave do not exist and are observed as light was soon confirmed by experiments. Because of its electric and magnetic properties, light is also electromagnetic radiation. Full electromagnetic spectrum – The full array of electromagnetic radiation, extends from the longest wavelength to the shortest wave length of gamma rays. Visible light occupies only tiny portion of the spectrum 400nm to 700nm. An opaque object emits electromagnetic radiation according to its temperature. Blackbody curve: represents the spread of the intensity of radiation emitted by any object over all possible frequencies. In a steady state, a blackbody must reemit the same amount of energy it absorbs. The curve describes the distribution of that reemitted radiation Wien’s Law: wavelength of peak emission is proportional to 1/temperature. The hotter the object, the bluer its radiation. Stefan’s law: As the temperature of an object increases, the total amount of energy it radiates increases rapidly. Total energy emission is proportional to the fourth power of the temp Doppler effect: motion induced change in observed frequency of a wave. The observe situated in front of the source measures a shorter wavelength, “blue shift,” while an observed behind the source sees a “redshift” - blue light has a shorter wavelength than red
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This note was uploaded on 03/24/2008 for the course ASTR 100Lxg taught by Professor Dappen during the Fall '07 term at USC.

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Midterm__2_Study_Guide - Astronomy Study Guide Chapter 4.8...

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