The goal of this activity is for students to investigate factors that affect energy storage in a capacitor and develop a model that describes energy in terms of voltage applied and the size of the capacitor.

In the Preliminary Observations, students observe a simple RC circuit that charges a capacitor and then discharges the capacitor through a light bulb. After a brief review of RC circuits, students will discuss the energy transformations in the circuit.

Students will then design and execute an investigation to determine how the charging voltage and capacitance affect the capacitor’s ability to store electrical energy.


  • Design and perform an investigation.
  • Draw a conclusion from evidence.
  • Understand that the energy stored in a capacitor is proportional to its capacitance and to the square of the voltage across it.