Name four ways that the interstellar medium reveals its presence
What will be an ideal response?
Hot gas glows as emission nebulae. Cool dust absorbs and scatters blue light more, making the distant stars appear redder in color than their spectra indicate they should. And if the cool dust and gas is dense enough, it can block starlight entirely and be revealed by its dark profiles against the starry background. Also, the dust grains can form molecules that are picked up with microwave or radio scopes.
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A negatively-charged rod is brought close to (but does not touch) two neutral spheres that are in contact with each other but insulated from the ground. If the two spheres are then separated, what kind of charge will be on the spheres?
A) The sphere near the charged rod becomes negative and the other one becomes positive. B) Both spheres become negative. C) The sphere near the charged rod becomes positive and the other one becomes negative. D) The spheres do not get any charge. E) Both spheres become positive.
At divergent boundaries, basaltic magma is generated by
A. Partial melting of mantle rock B. Partial melting of continental crust C. Partial melting of ocean crust
A diffraction grating with 11 800 lines/cm will exhibit the first-order maximum for light of wavelength 416 nm at what angle? (1 nm = 10?9 m)
a. 0.513° b. 0.281° c. 58.8° d. 29.4° e. 15.1°
"Weightlessness" occurs when an object
a. has zero acceleration. b. is in free fall. c. is midway between Earth and the Moon. d. loses weight.