5F30.40 - Leaky Capacitor
Illustrate an electrical system prevelent in natural systems. A current source charges a capacitor and is discharged through a parallel variable resistor.
Set up the circuit shown in the diagram. Make sure to use fluke amp and volt meters so that a quick change can be seen. Make sure the range on the meters are set on manual mode at a value large enough so that the meter does not "OL" and have to switch scales mid-observation. Set up a camera to read the multimeter outputs. Likely will need to label the multimeters for ease of explanation.
Hold down the momentary contact connected to the charging portion of the circuit until the capacitor is full. Release the switch and then hold down the momentary contact connected to the discharging portion of the circuit. This shows a drain of the stored charge on the capacitor. Then, if you hold down both momentary contact switches and allow the system to come to a steady state, you will see that the parallel resistor constantly bleeds off some of the stored charge on the capacitor. Then change the value of the variable resistor and repeat. Observe the difference in the new steady state values.
You can compare this electrical system to the demonstration 2C10.15, which represents the capacitor as a bucket of water and the parallel resistor as a small hose at the bottom of the bucket. The diameter of the hose represents the value of the resistance of the parallel resistor. When the resistance is low, that is equivalent to a hose with a large diameter, allowing more flow of water/charge from the bucket/capacitor. When the resistance is high, that is equivalent to a hose with a small diameter, allowing for a slower rate of leakage from the bucket/capacitor.