Something terrible just happened (death in the family, major health issue, etc.) and I do not feel that I can take the exam. What should I do?
Contact course staff immediately. If you can document the problem and it falls under the heading of an excusable absence then you should NOT take the exam. Bring the documentation to the Physics Department Undergraduate Office in 231/233 Loomis and you will be excused from the exam. We CANNOT excuse an exam after you have taken it!
Make sure that your absence is excusable before deciding not to take the exam, because your grade will suffer less if you take the exam and do poorly than if you don't take it and get a 0.