AP® Physics 1 & 2

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Capacitor Arrangements: Maximum Energy: Student Discussion


Three students have the task of designing a circuit that will store the maximum amount of electrical energy. The circuit contains a 12-volt source and two capacitors ($470\mu F$ and $330\mu F$) that are connected in series with the battery.

Student 1 insists that the present arrangement will store the most energy.

Student 2 thinks that the two capacitors should be arranged in parallel to store the most energy.

Student 3 argues that the $330\mu F$ capacitor should be removed and that the $470\mu F$ capacitor alone will store the most energy.

Which student is correct and why?


Student 1 is correct because capacitors connecting capacitors in series always ensures the charge on each capacitor is the same and a maximum.


Student 2 is correct because each capacitor will have the same maximum voltage, the battery voltage.


Student 3 is correct because anytime you add a smaller capacitor to a larger capacitor the equivalent capacitance is lower than either individual capacitor.


The best way to maximize the electrical energy is to remove the $470\mu F$ capacitor because the energy and capacitance have an inverse relationship.