Induction, Attraction, and Repulsion: Nylon Stockings

Grade Levels: 5 - 6

Objectives

• Students will observe, infer, classify, predict, communicate, formulate hypotheses, identify and control variables, and experiment.

Materials

• Cool, dry day
• Sheer nylon stocking
• Clean lightweight plastic (such as a fresh vegetable bag from grocery store)
• Smooth wall, chalkboard, or cork board

Procedures

1. Holding it by the top, place the nylon stocking against the wall.
2. Use the plastic to rub and smooth the stocking against the wall. It is best to rub with long strokes in one direction from top to toe. Do this about 20 times.
3. Release your hold on the top of the stocking.
4. Have students describe what happened.
5. Keeping an arm's length away from the stocking, grasp at the top and slowly pull it away from the wall. Be sure nothing comes near it.
6. Still holding it at arm's length, ask students if they observe any difference in the stocking.
7. Slowly bring the stocking toward you. Ask students to describe what happened.
8. Can they explain why this happened?

   This activity demonstrates induction and the attraction and repulsion of like and unlike static charges. Be sure the nylon you use has been washed thoroughly in clear water so any anti-cling treatment has been removed.

   At first the nylon will hang limply against the wall. As the plastic is rubbed on the nylon it will remove electrons from the stocking, giving the stocking a positive charge. By the time the stocking has been stroked 20 times it should smooth out and cling to the wall without support. This is caused by a form of induction explained earlier in the section on static electricity.

   When the stocking is pulled away from the wall and held at arm's length it will fill out in all directions as if an invisible leg were inside. This is because the entire stocking has a positive charge and like charges repel or push away from each other.

Excerpted from Hands-On Physical Science Activities for Grades K-8.