A distant galaxy is emitting light from the helium spectrum at 388.9 nm. On Earth the wavelength of the light from this galaxy is measured to be 540.6 nm
Estimate how far from Earth (in light-years) this galaxy is if the Hubble constant has the value 22 km/s per million light-years. (c = 3.00 × 108 m/s, 1 ly = 9.461 × 1015 m, 1 y = 3.156 × 107 s)
4.3 × 109 ly
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If the diameter of a wire increases, its resistance
a. increases. b. decreases. c. does not change. d. will increase or decrease depending on the composition. e. will change in a way that can not be determined.
Atoms of materials that are good conductors of electricity have
A. only electrons, and so these electrons are easily moved. B. mostly protons; thus, the negative charges jump easily from atom to atom. C. outer electrons which are loosely bound and thus easily moved. D. no electrons; thus, any that are given to them are easy to move about.
The cosmic microwave background radiation was released shortly after the formation of the first stars
a. True b. False Indicate whether the statement is true or false
The very first stars in the universe were made of
A) hydrogen and helium. B) hydrogen and helium, 10% heavy elements. C) hydrogen and helium, 0.1% heavy elements. D) hydrogen and helium, 2% heavy elements.