# unit 6 - Unit 6 If a light source is receding from us we...

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Unit 6 If a light source is receding from us we say it has a Red shift. This means the light source will appear red. B. Incorrect. If a star is moving away from us, its light will be Doppler shifted toward the _______. A. Red If a star is receding from us the light it emits will be _____. A. Red shifted. If a source, emitting light of wavelength L, is approaching us at speed v, and if c is the speed of light; the change in wavelength dL that we will observe is ____. C.. dL / L = v / c . The Doppler effect _____. A.. Is the change in observed wavelength from a wave source that is approaching or receding from us . . If two stars have the same spectral class and are of different sizes, they must have different _____. B.. Absolute magnitudes. If two stars of the same spectral class have different absolute magnitudes, they must have different ___. E.. Sizes. The Stefan-Boltzmann law is _____. A.. The total energy emitted per unit area per unit time is proportional to the fourth power of the temperature in degrees Kelvin. If two stars of the same spectral class have different absolute magnitudes, they must have different ___. E.. Sizes. The total energy emitted per unit area by a black body is proportional to the ___ power of the Kelvin temperature. C.. Fourth. If a star is approaching us at 0.01 the speed of light and it is emitting 500.0 nm light, we will see a wavelength shift of __. D.. 5.0 nm toward the blue. If a star is receding from us at 0.1 times the speed of light. A 700 nm wavelength light emitted by it will appear as __ nm light to us. D. 770. A galaxy is moving away from us at 0.01 times the speed of light. If a spectral line of 500 nm is emitted from the galaxy, what wavelength will be observed on Earth? C.. 505 nm. If another galaxy was moving toward us at a speed which is 0.1 times the speed of light, the Doppler shift (change in wavelength) of a spectral line of 800 nm would be __ . B.. 80 nm toward the blue.

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These curves show the continuum radiation produced by two stars. Which star has the lower temperature? B.. T1. The perfect radiator with the larger temperature is ____. B.. T2. Two stars have the same surface area, The first star, S1, has a Kelvin temperature which is two times as high as the second star, S2. Which star is the brighter and by how many times? F.. Star S1 is sixteen times brighter than S2. . The parallax of a star is the angle through which the star appears to move (against the background stars) in the course of a year (corrected for its position relative to the ecliptic). C. Wrong -- half the angle in a year. In the diagram, which angle is the star's parallax?
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unit 6 - Unit 6 If a light source is receding from us we...

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