AP Physics 1 Question 29: Answer and Explanation
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9. A wire is split into 4 segments, and they have resistances of R, 2R, ½R, and 4R in that order. Which of the following sets of changes from one segment to the next could correctly account for the changes in resistance?
R→2R 2R→4R 4R→R
- A. length is doubled area is doubled radius is doubled
- B. length is doubled area is halved radius is doubled
- C. length is doubled area is doubled radius is quadrupled
- D. length is halved area is doubled radius is doubled
Correct Answer: B
B The formula for resistance is R = . Keep in mind that Area = πr2, and the only answer that fits all three changes is (B).