Exploration 26.1: Energy

Please wait for the animation to completely load.

Wait for the calculation to finish.  As you move the bottom capacitor (and allow the applet to finish calculating after each move), the graph shows the stored energy as a function of separation distance between the plates (position is given in millimeters, charge is given in nanocoulombs, and energy is given in nanojoules).  Restart.   

1. Given that the stored energy (the potential energy) is QV/2, what is the voltage difference between the plates? 
2. Does the voltage difference between the plates change? 
3. How does the capacitance change as you move the plates? 
4. What is the area of the plates for this capacitor?
5. Why does the charge change as you move the plates?
6. As you move the plates closer together, does the stored energy increase or decrease? 
7. Does that mean you would need to do positive work to push the plates together or pull them apart?  Explain.
8. Since potential energy U = QV/2, if V is kept constant, what is U (potential energy) as a function of the separation distance?  Verify that this is the relationship shown on the plot.

Exploration authored by Anne J. Cox.
© 2004 by Prentice-Hall, Inc. A Pearson Company