If one waits for a time equal to two half-lives for a certain radioactive material, all of it originally present will have decayed completely.A
Indicate whether the statement is true or false
F
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An atmosphere containing enough greenhouse gases can trap heat and raise the temperature of a planet's surface
Indicate whether the statement is true or false
The star Vega has an apparent visual magnitude of 0.03 and the star HR 4374 has an apparent visual magnitude of 4.87 . It has been determined that both stars are at the same distance from Earth. What does this information tell us about the two stars?
a. Vega must be closer to Earth than HR 4374. b. Vega must be farther from Earth than HR 4374. c. Vega must produce less energy/second than HR 4374. d. Vega must produce more energy/second than HR 4374. e. Vega will appear fainter to us than HR 4374.
A dark object sitting in sunlight gets warm. The sun radiates light because it is very hot, much hotter than the object. So should we categorize the radiation that the object receives from the sun as being heat Q or energy transferred by electromagnetic radiation [EER]? Be prepared to justify your answer with an argument (multiple reasonable arguments are possible).
A. Heat Q B. Energy transfer [EER] C. It depends on how we define the system boundary. D. It doesn’t matter.
If total internal reflection occurs at a glass-air surface:
a. no light is reflected. b. no light is refracted. c. light is leaving the air and hitting the glass with an incident angle less than the critical angle. d. light is leaving the air and hitting the glass with an incident angle greater than the critical angle.