Question 8 of 15 Map presented by Physics sapling learning COLLEGE On the Moon\'

Question

Question 8 of 15 Map presented by Physics sapling learning COLLEGE On the Moon's surface, lunar astronauts placed a corner reflector, off which a laser beam is periodically reflected. The distance to the Moon is calculated from the round-trip time. The Earth's atmosphere slows down light. Assume the distance to the Moon is precisely 3.84 x 108 m, and Earth's atmosphere (which varies in density with altitude) is equivalent to a layer 20.0 km thick with a constant index of refraction n 1.000293. What is the difference in travel time for light that travels only through space to the moon and back and light that travels through the atmosphere and space? Number

Explanation / Answer

Distance between Moon and earth S = 3.84 x 10 8 m

Thickness of the atmosphere S ' = 20 km

                                                = 20 x 10 3 m

Speed of light in space c = 3 x 10 8 m / s

Speed of light in atmosphere v = c / n

Where n = index of refraction of atmosphere = 1.000293

So, v = 299.912 x 10 6 m / s

Time travel through space t = 2S / c

                                        = 2.56 s

Time travel to atmosphere ans space t ' = [2S' / v ] + [2(S-S')/c ]

                                                          = [1.333724 x 10 -4 ] + 2.5598

                                                         = 2.560000039 s

Time difference t ' - t = 0.000000039 s

                               = 39 x 10 -9 s

                               = 39 ns

Related Questions

Navigate

• Browse (All)
• Browse Q
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.