The radiocarbon content of 14C decreases after the death of a living system with a half-life of 5730 y. If an archaeologist working a dig finds an ancient firepit containing some partially consumed firewood and the wood contains only 12.5 percent of the 14C content of an equal carbon sample from a present-day tree, what is the age of the ancient site?
17 190 years
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Starting from very far away, an object is moved closer and closer to a concave lens, eventually reaching the lens. What happens to its image formed by that lens? (There could be more than one correct choice.)
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A laser with a power of 1.0 mW has a beam radius of 1.0 mm. What is the peak value of the electric field in that beam?
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