Education Technology

Charging Up, Charging Down: Exponential Models

Published on 07/02/2009

Activity Overview

In this activity, students' will use a voltage probe to collect voltage data from a discharging capacitor. They will model potential data using an exponential function.

Before the Activity

  • Connect the voltage probe to Channel 1 on the CBL 2™ or Vernier LabPro®
  • Connect the CBL 2 or LabPro to the calculator using the Unit-to-Unit cable
  • See the attached PDF file for detailed instructions for this activity
  • Print pages 175 - 182 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to your class.

    Follow the Activity procedures:

  • Connect the voltage probe and resistor across the capacitor
  • Verify that the wires are in the correct position to confirm that the capacitor is charged
  • After the capacitor is charged, remove the battery from the circuit and begin data collection
  • Examine the graph of potential versus time displayed on the calculator and record the y-intercept on the Data Sheet
  • Graph the capacitor discharge described by the expoential model
  • Record the time at which the capacitor voltage reaches half its initial value
  • After the Activity

    Students' will complete the Data Collection and Analysis Sheet and answer the questions listed in it.

    Review student results

  • As a class, discuss questions that appeared to be more challenging
  • Re-teach concepts as necessary