B: Why would an ultraviolet telescope not work very well on the Earth\'s surface
ID: 110127 • Letter: B
Question
B: Why would an ultraviolet telescope not work very well on the Earth's surface, nor on the top of a mountain top?
C: Which star has the strongest balmer lines? Star 1 is class M star Star 2 is a class B star Star 3 is a class A star
D: Star A and Star B both have an apparent magnitude of 4.0, but star A has an absolute magnitude of 1.0 and star B has an absolute magnitude of 7.0. Which statement is correct? Star A and star B appear to have the same brightness, but star A is more luminous than star B Star B appears brighter than star A, but actually star B and star A are equally luminous Star A and star B appear to have the same brightness, but star B is more luminous than star A Star A appears brighter than star B, but actually star B and star A are equally luminous
Explanation / Answer
B. Since the atmosphere of the earth is opaque to higher frequency electromagnetic radiation eg ultraviolet light and hence absorbs it completely, so astronomy should be done using ultraviolet telescopes from the space. In order to observe the cosmic sources ultraviolet radiation must be above the earth's surface. This is the reason that ultraviolet radiation does not work very well on the earth's surface nor on the top of a mountain top.
C. Balmer series are the spectral emission lines of the hydrogen atom that result from higher level down to the lower energy level The pattern of absorption line changes from class O to M. The balmer lines produced by the hydrogen are very strong in A and B stars and nearly absent in K and M stars. Since the balmer line of A star is strong therefore Star 3 has the strongest balmer line followed by Star B which is the B class star who has medium balmer lines and lastly Star 1 which is the M star whose Balmer lines are very weak.
D. Absolute magnitude is the intrinsic brightness of the object whereas the apparent magnitude tells how bright an object appears from the earth. If the two stars have the same apparent magnitude but different magnitude which means that they are located at different distances from us. Star A and Star B appear to have same brightness but actually Star B is more luminous than star A.
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