Vernier Electrostatics Kit - Manual (Page 2)

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Performing Experiments with the Faraday Pail and the Vernier
Charge Sensor
The key part to this kit is the Faraday Pail and Cage. When the Charge Sensor is
attached to the Pail, the Pail can be used to qualitatively and quantitatively measure
charge on objects. Follow these instructions to set up the equipment.
1. Place the plastic disk that holds the Faraday Pail and cage on the Ground Plane.
2. Place the Faraday Pail and the Cage on the disc.
3. Connect the black lead from the Charge Sensor to the Ground Plane.
4. Connect the red lead from the Charge
Sensor to the Faraday Pail.
5. Connect the Charge Sensor to an interface,
such as a LabQuest ® 2, LabQuest, or
LabPro ® .
6. Connect a Grounding Wire between the
Cage and the Ground Plane.
7. Ground the system and zero the sensor by
pressing and holding the Reset button on
the sensor.
8. Now insert an object into the center of the
Faraday Pail. While the object is in the
Pail, the Charge Sensor will display the
charge.
Quantitative measurement of electrostatic charge can be challenging. Many factors
enter into the buildup of electrostatic charge and your ability to measure the charge.
The Charge Sensor is a very sensitive device and it can detect charge on objects
where you may not expect to see it, e.g., your body. Your success is also a function
of atmospheric humidity. Electrostatic studies are difficult in humid environments
because objects discharge quickly through multiple paths.
The Charge Sensor contains a range switch. You need to select a range that is
appropriate for the experiment and environmental conditions. For example if you are
measuring a small electrostatic charge, the smallest range setting on the sensor may
be appropriate; however, if the sensor is reading its maximum value, you may want
to switch to a higher range.
Note: As you collect data for different situations, you will need to zero the
Charge Sensor since it is extremely easy to pick up stray charges. If the sensor
reading appears to drift, simply press the Reset button on the sensor between
data-collection runs. A good practice is to zero the Charge Sensor before each trial.
Sample Experiments
There are a variety of experiments that can be performed with this kit and a
Charge Sensor. Below you will find three detailed examples. You might want to try
them out to learn more about the equipment. Those examples are followed with brief
descriptions of other experiments.
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Learning to use Faraday Pail and the Vernier Charge Sensor –
How much electrical charge can your body carry?
The following experiment is a great introduction to this kit and the Vernier Charge
Sensor. The activity demonstrates the sensitivity of the equipment. In the activity the
user explores the charge that the body can carry and how to discharge the sensor and
the body.
1. Attach the Charge Sensor black lead to the Ground Plane.
2. Attach the Charge Sensor red lead to the Faraday Pail.
3. Connect a Grounding Wire between the Cage and the Ground Plane.
4. Ground the system and discharge the sensor by pressing and holding the Reset
button on the sensor.
5. Do not attach the grounding strap to your arm, because the purpose of this
experiment is to show how your body can become charged.
6. Scuff your shoes on the floor. Insert a
finger into the Faraday Pail without
touching the Pail. What does it read?
[The answers will vary but should be
different from zero.]
7. Remove your finger. What does it
read? [Close to zero.]
8. Explain your findings. [Scuffing the
shoes built up a charge on the body.
The Faraday Pail and Charge Sensor
detected the charge. When the finger
is in the Pail, the sensor detects a
charge. When the finger is removed, it detects no charge. The magnitude and sign
of the charge will depend upon the composition of the flooring and shoes.]
9. Touch the Ground Plane with your finger.
10. Insert a finger into the Faraday Pail without touching the Pail. What does it read?
[Should be close to zero]
11. Remove your finger. What does it read? [Should be close to zero]
12. Explain your observations. [Touching the Ground Plane removes the charge from
the body. The charge on the body should be zero. The Charge Sensor reading
should be close to zero regardless of whether the finger is in the Pail or not.]
13. If possible, scuff your shoes on a different type of flooring. Insert a finger into
Pail. What does it read? [Answers will vary but should not be zero.]
14. Remove your finger. What does it read? [Close to zero]
15. Explain your findings. [Again a charge should be detected on the body. The
magnitude and sign of the charge will depend upon the composition of the
flooring and shoes.]
16. Insert your finger into the Pail. Touch the Pail and remove your finger. What does
the sensor read? Explain findings. [Touching the Pail leaves a charge.]
17. Ground the Pail and zero the sensor by pressing and holding the Reset button on
the sensor.