Vernier Electrostatics Kit - Manual (Page 3)

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18. Scuff your shoes on the floor. Insert a finger into the Pail without touching. What
does it read? [Should be a non-zero number.] Remove your finger. Now move
your finger toward the wire Cage. What does the sensor read? [It should remain
unchanged from before.] What does that say about the Cage? [The Cage shields
the Faraday Pail from external charges.]
Observe the separation of charge using common materials
Rub dissimilar materials together to generate a charge on each. Use the Faraday Pail
and Charge Sensor to measure the sign of the charge on each. The materials
investigated are wool fabric, vinyl pad, nylon rod (white) and PVC rod (gray).
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. Attach the grounding strap to your wrist.
5. Ground the system and discharge the
sensor by pressing and holding the Reset
button on the sensor.
6. Fold the vinyl in half, in quarters, and
then in eighths. The peak that forms from
these folds will be an object for which
you will measure charge. Rub the white nylon rod back and forth along the peak
of this vinyl. Insert the rod into the Pail without touching the Pail. What is the
sign of the charge? [Positive]
7. Insert the vinyl peak into the Pail without touching the Pail. What is the sign of
the charge? [Negative]
8. Fold the wool in half, in quarters, and then in eighths. Rub the gray PVC rod back
and forth along the peak of the wool. Insert the rod into the Pail without touching
the Pail. What is the sign of the charge? [Negative]
9. Insert the wool peak into the Pail without touching the Pail. What is the sign of
the charge? [Positive]
Explore charging by induction using the Charge Separators
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. Attach the grounding strap to your wrist.
5. Ground the system and discharge the sensor by pressing and holding the Reset
button on the sensor.
6. Rub the Charge Separators together.
7. Place the white Charge Separator in the Pail being careful to not touch the side of
the Pail. What is the sign and magnitude of the reading? [Should be positive.
Magnitude will vary.]
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8. While the white Charge Separator is in the
Pail, ground the Pail by touching it with
your finger. What does the sensor read?
[Should be close to zero.]
9. Remove your finger. What does the sensor
read? [Should be close to zero.]
10. Remove the Charge Separator. What is the
sign and magnitude of the charge as
shown by the sensor? [Should be negative
and have a magnitude similar to that seen
in #7.]
11. Move the Charge Separator back into the
Cage; what is the sign of the charge? What
is the magnitude of the charge? [Should be
close to zero.]
12. Explain your results. [The charge on the Charge Separator is positive. When it is
inside the Pail, the sensor shows a positive charge. When the Pail is grounded,
negative charge from the grounding plane is attracted to the Pail leaving the Pail
negative. These positive and negative charges cancel and the sensor reads zero.
When the ground is removed, a negative charge is left on the Pail, but it is being
canceled by the positive charge on the Charge Separator; therefore the sensor still
reads zero. When the Charge Separator is removed, the negative charge on the
can is no longer cancelled by the positive charge on the Charge Separator, and
the sensor reads negative. When the Charge Separator is placed back into the
Pail, the charges now cancel each other and the sensor again reads zero.]
13. Repeat with the gray Charge Separator and explain your results. [The charge on
the Charge Separator is negative. When it is inside the Pail, the sensor shows a
negative charge. When Pail is grounded, negative charge on the Pail is repelled to
the grounding plane leaving the Pail positive. These positive and negative
charges cancel and the sensor reads zero. When the ground is removed, a positive
charge is left on the Pail, but it is being canceled by the negative charge on the
Charge Separator; therefore the sensor still reads zero. When the Charge
Separator is removed, the positive charge on the Pail is no longer cancelled by
the negative charge on the Charge Separator and the sensor reads positive. When
the Charge Separator is placed back into the Pail, the charges now cancel each
other and the sensor again reads zero.]