Question
In an experiment, three microscopic latex spheres are sprayed into a chamber and become charged with +3e, +5e, and −3e, respectively. Later, all three spheres collide simultaneously and then separate. Which of the following are possible values for the final charges on the spheres? Select two answers.
Final Answer
(a) and (d)
Solution video
OpenStax College Physics for AP® Courses, Chapter 18, Problem 2 (Test Prep for AP® Courses)
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Video Transcript
This is College Physics Answers with Shaun Dychko. Three microscopic latex spheres are sprayed into a chamber and they become charged; the first one has a charge of positive 3 times the elementary charge, the second one is positive 5 and the third one is negative 3 times the elementary charge. Later on, the three spheres collide and then this charge that each of them has gets redistributed among the three spheres and the question is what are two possible distributions of charge among the three spheres after the collision? We need to figure out what is the net charge to begin with. So we have positive 3 times the elementary charge plus 5 minus 3 is a total of positive 5 times the elementary charge so whatever the distribution is after collision, it's going to have to have the same net charge and after collision if we ended up with having a positive 4, a negative 4 and a positive 5 then that would have a net charge of positive 5 and here we have fractional charges which are impossible so we can exclude option (b). This net charge here... well, negative 8 plus 7 is negative 1 plus 5 is positive 4 and so the net charge is not 5 anymore, it's 4 and charge cannot just disappear or be created so that means (c) is excluded and just to confirm, this works out to positive 5 because this is 12 minus 7 this 5 so (a) and (d) are the answers.