The Versorium Move? (Think About Charges and Electrons.) ______

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! ______Versorium Lab Versorium Lab______! ______Problem: A versorium is a device that was first described in 1600 by Sir William Gilbert. Why does a !versorium turn? Hypothesis: !(Complete the six predictions in the Data Table using complete sentences.) Materials foam cup aluminum foil scissors plastic foam plate !wool fabric pencil paper Procedure PART 1 Aluminum Foil Versorium 1. Cut a piece of aluminum foil approximately 3 cm by 10 cm. 2. Make a tent out of the foil strip by gently folding it in half in both directions. 3. Push a pencil up through the bottom of an inverted cup. CAUTION: Avoid pushing the sharpened pencil against your skin. Balance the center point of the foil tent on the point of the pencil as shown. 4. Record your predictions and observations in the data table. 5. Predict what will happen if you bring a foam plate near the foil tent. Record your prediction in the data table. 6. Predict what will happen if you rub the foam plate with a piece of wool fabric and then bring it near the foil tent. Record your prediction. 7. Predict what will happen if you bring the rubbed wool near the foil tent. Again record your prediction. 8. Test each of your three predictions and record your observations in the data table. ! Data Table and Observation Unrubbed Foam Foam Plate Rubbed Rubbed Wool Plate Wool Fabric Fabric Aluminum Tent: ! Prediction ! ! ! !

PART 2 Paper Tent Versorium 9. What do you think would happen if you used a paper tent versorium instead of the aluminum foil? Record your prediction for each of the three tests. 10. Test your predictions and record your observations! in the data table. ! Data Table and Observation Unrubbed Foam Foam Plate Rubbed Rubbed Wool Plate Wool Fabric Fabric Paper Tent: ! Prediction ! ! ! !

Paper Tent: ! Observation ! Electricity ! ! !

Conclusion: (Include data from the data chart and observations to complete the conclusion. How did your hypothesis differ/agree with what you observed and why? How did the foil tent versorium move compared to the paper tent versorium? Explain your answer with reference to !charging by friction, conduction, or induction.) ______Questions: 1. Why did the versorium move? (Think about charges and electrons.) ______

© Pearson Education, Inc., publishing as Pearson Prentice Hall. All rights reserved. ______2. During this lab, why is it important to avoid touching the foam plate or the wool with other objects before testing them with the versorium? ______! ! ! Explanation: The foam plate has been charged with negative electric charge and the wool fabric has been !charged with positive electric charge. The aluminum sheet is a conductor which has free electrons and it is not charged. As we bring the charged plate near the versorium the free electrons of the aluminum sheet are in the electric field of the negatively charged plate and for this reason they are repelled and move to the far end of the versorium, which now is negatively charged. Thus, the end of the versorium, which is nearer to the plate is now positively charged, as you can see in the two pictures. Thus, when a metallic conductor is in the area of an electric field, then, the free electrons of the metallic conductor move to the far end of the conductor, if the electric field is due to a negative electric charge, or they move to the nearer end of the conductor if the electric field is due to a positive electric !charge. This phenomenon is called electrostatic induction.