SAT Subject Physics Practice Question 595: Answer and Explanation

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Question: 595

6. Scientists can determine whether a star is approaching the earth by looking at its

A. red shift.
B. blue shift.
C. rate of shimmer.
D. brightness.
E. absolute magnitude.

Correct Answer: B


The correct answer is (B). The Doppler Shift is useful for all kinds of waves, including light. When a star or any object that is producing waves approaches, the individual wave fronts are contacted at a higher rate. In the case of stars, the higher rate at which the wave fronts are contacted causes the starlight to move toward the blue range.

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