Electrification by contact

Figure 1

When a neutral conductive object is brought into contact with a negatively charged object, the two together function as a single large object. The excess electrons on the negatively charged object, which repel each other, now have more space to spread out to distribute the negative charge. Electrons from the charged object flow to the uncharged object thus charging it. If the two negatively charged objects are then separated, they each maintain their negative charge.

einstein™Tablet+ with MiLAB or Android/iOS Tablet with MiLAB and einstein™LabMate Electrostatic Charge sensor Test leads with BNC connector Faraday ice pail Conductive sphere Insulating rod Stand High voltage power supply

Charge sampler

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2.

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5.

Launch MiLAB ( ).

Connect the Electrostatic Charge sensor to one of the ports on the einstein™Tablet+ or einstein™LabMate.

Connect the test leads to the Electrostatic Charge sensor.

Assemble the equipment as shown in Figure 1. a. Connect the red lead of the Electrostatic Charge sensor to the inner cylinder of the Faraday ice pail. b. Connect the black lead to the outer cylinder of the Faraday ice pail. c. Connect the conductive sphere to the high voltage output of the high voltage power supply.

Make sure that only the Electrostatic Charge sensor is selected.

Note: You may need to ground the outer cylinder of the Faraday ice pail.

Program the sensor to log data according to the following setup: Electrostatic Charge Sensor

Charge, 25 nC (nC)

Set As Zero

ON

Rate:

10/sec

Duration:

2 Min

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2.

Turn on the power supply.

Short circuit the two leads of the Electrostatic charge sensor. To short circuit the sensor, connect the positive (red) and negative (black) leads.

3.

Tap Run (

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Ground the charge sampler to remove any residual charge from it.

Lower the charge sampler into the inner basket of the Faraday ice pail. Observe the resulting graph.

6.

Tap Stop (

) to stop collecting data.

7.

Tap Save (

) to save data.

8.

Short circuit the two leads of the Electrostatic charge sensor.

9.

Tap Run (

) to begin recording data.

) to begin recording data.

10. Touch the conductive sphere with the charge sampler, and then lower the charge sampler into the inner basket of the Faraday ice pail. Observe the resulting graph.

11. Tap Stop (

) to stop collecting data.

12. Tap Save (

) to save data.

13. Short circuit the two leads of the Electrostatic charge sensor.

14. Tap Run (

) to begin recording data.

15. Touch the conductive sphere with the charge sampler a second time, then lower the charge sampler into the inner basket of the Faraday ice pail. Does the graph change? Explain your observations.

16. Tap Stop (

) to stop collecting data.

17. Tap Save (

) to save data.

18. Short circuit the two leads of the Electrostatic charge sensor.

19. Tap Run (

) to begin recording data.

20. Now ground the charge sampler to remove any residual charge from it, then repeat step 7. Explain the changes in the graph.

21. Tap Stop (

) to stop collecting data.

22. Tap Save (

) to save data.

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Is the conductive sphere charged positively or negatively?

Explain how the spheres were charged.

Explain the process by which you charged the charge sampler.