Van de Graaff Electrostatics Lab
This lab is one of the most popular for obvious reasons! In it, students will investigate static charges on balloons, an electroscope, and the Van de Graaff generator. This is a straight-forward lab, but some teacher set-up time is needed. Teachers will need to provide a Van de Graaff generator, an electroscope, and enough balloons and tissue paper for each student. Make sure that none of the students are allergic to latex and use cheap tissue paper, the kind without any lotion if possible. Also, clean the Van de Graaff dome with alcohol before use to get the best effects possible.
The lab will have students inflating and charging the balloons to see how many pieces of tissue paper it can pick up. The teacher will then use an electroscope to demonstrate electrical induction. Finally, the teacher will use the Van de Graaff to demonstrate the properties of an electric field with strips of tissue paper taped to the dome. After this, the instructor will then have an opportunity to perform some classic demonstrations with the Van de Graaff, including forming a human chain (of volunteers), stacking pie plates on top of the dome, perform some hair-raising demos, lighting up a fluorescent tube, or any other number of cool demos. (Just Google some demos and a lot of stuff will pop up.)
I tend to do the lab as a teacher-led, whole class activity, keeping everyone on the same question until we are ready to move on.
This lab is best suited for conceptual physics, regular physics, special ed science, or general science. This lab is appropriate for both high school and middle school students.
Topics discussed include electrostatics, static charges, static electricity, static discharge, conductivity, insulators, electron flow, charging by induction, attraction, and repulsion.
The lab itself should take anywhere from 25 to 35 minutes to complete, leaving plenty of time for individual student questions, or for the teacher to facilitate a classroom discussion. There will also be time left over to have the students perform demos and get up-close-and-personal with the Van de Graaff generator.
Tips and hints:
• When inflating the balloons (I do not use the word “blow”), ask first if any students need help. You will be surprised at how many students cannot either inflate a balloon or cannot tie a knot.
• If students use any hair products, have them rub it on their shirts instead. Styling products tend to act as great insulators, leaving the balloons with little charge.
• Try to do the lab on a relatively dry day, for best results. Humidity can lend to disappointing results.
• Use the cheapest tissue possible, preferably ones without any lotions infused in them. What feels better on the nose does not work as well for holding a charge.
• Always ask for volunteers to form a “human chain” when using the Van de Graaff generator. Some students are plain frightened of the machine!
• Before doing the lab, especially after lunch, have the students wash their hands. Oils on hands act as wonderful insulators.
• Clean the Van de Graaff dome, especially before the first demo of the day. Teachers rarely remember to clean it off after their last class is done touching it. Oils are the enemy!
• Do not let kids try and take balloons out of your class. Have them pop them all before they leave. Just inform teachers next door to you that they will hear some popping sounds. This is not gunfire! Your fellow staff members will thank you.
• Save a few minutes towards the end of class for clean up. There is no reason you need to clean everything, and it does get quite messy. The custodial staff will appreciate your efforts!
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