Physics Final Exam Questions Study Guide 2024 Updates

If a sample of a radioactive isotope has a half-life of one year, how much of the original sample will be left at the end of the second year? At the end of the third year? At the end of the fourth year? {Ans: After each half-life, ½ of the amount present at the beginning has decayed. So after the 1st year, ½ of the original amount is gone. After the 2nd year, ½ of that is gone, or ¼ of the original amount. After the 3rd year, ½ of that or 1/8 the original amount. After the 4th year, ½ of that or 1/16 the original amount.}What path does light want to take? {Ans: The quickest path.}The energy ratio of a photon to its frequency. {Ans: Planck's constant}Why is a chain reaction more likely to occur in a big piece of uranium than a small piece? {Ans: In a big piece, the ejected neutrons are more likely to strike another nucleus before exiting the piece due to geometry. In a larger piece, more uranium atoms & a smaller surface area are presented to the neutrons. A smaller fraction of free neutrons escape before triggering another