A galaxy is observed receding from Earth with a speed of 9800 km/s.A redshifted spectral line originating in the galaxy is compared to the same spectral line originating in the laboratory.If Hubble's law is valid for this galaxy,what is the ratio of the wavelength of the redshifted line to that of the unshifted line if the Hubble constant is 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) A) 1.033 B) 1.052 C) 1.072 D) 1.091 E) 1.130

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Quizplus · Accepted Answer

The redshift z can be calculated using the formula z = v/c, where v is the velocity of the galaxy and c is the speed of light. Here, z = 9800 km/s / 3.00 × 10^5 km/s = 0.03267. The ratio of the redshifted wavelength to the unshifted wavelength is 1 + z = 1.03267, which is approximately 1.033.

A Galaxy Is Observed Receding from Earth with a Speed