Question
Which of the following can be explained on the basis of conservation of charge in a closed circuit consisting of a battery, resistor, and metal wires?
1. The number of electrons leaving the battery will be equal to the number of electrons entering the battery.
2. The number of electrons leaving the battery will be less than the number of electrons entering the battery.
3. The number of protons leaving the battery will be equal to the number of protons entering the battery.
4. The number of protons leaving the battery will be less than the number of protons entering the battery.

(a)

Solution Video

# OpenStax College Physics for AP® Courses Solution, Chapter 20, Problem 1 (Test Prep for AP® Courses) (0:51)

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Video Transcript

This is College Physics Answers with Shaun Dyhcko. The answer to this question is A because the electrons are the charge carriers that move through the circuit. So electrons will come out of the negative terminal of the battery and they'll flow through the circuit and however many electrons come out of this terminal has to be equal to the number of electrons going into the other terminal. Otherwise there would be a build-up of electrons within the wire or they would be if there were more going into the positive than were coming out of the negative, or conversely you would have if there were less going into the positive terminal then it would mean the electrons were disappearing somewhere. You know, those things are possible because of conservation of charge. So there we are, A is the answer.