Roughly how far across is the Milky Way?
A. 10 million light-years
B. 25,000 light-years
C. 25 light-years
D. 100,000 light-years
Answer: D
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Helium-neon laser light has a wavelength in air of 632.8 nm. What is the energy of a single photon in the beam? (h = 6.626 × 10^?34 J?s and c = 3.00 × 10^8 m/s)
a. 3.14 × 10^?19 J b. 5.40 × 10^?19 J c. 7.62 × 10^?19 J d. 1.15 × 10^?18 J
Why must the string held in the student's hand be pulled at a uniform rate?
Suppose that hydrogen, rather than iron, had the lowest mass per nuclear particle. Which of the following would be true?
A) Stars would be brighter. B) Stars would be less massive. C) All stars would be red giants. D) Nuclear fusion could not power stars.
At the Earth's north pole, the north celestial pole is directly overhead and stars near the horizon travel in straight lines
a. straight up from the horizon. b. straight up from the horizon slanting toward the right. c. straight up from the horizon slanting toward the left. d. parallel to the horizon.