Fun with Electrostatics!

A couple of weeks ago I started the unit on electricity and magnetism in my physics classes. I was really nervous about teaching this unit more than all the others because, although we are all familiar with electricity, the phenomenons behind what makes electricity possible are invisible to the naked eye. In a way, electricity just seems like magic.

Part of the unit involves talking about electroscopes. An electroscope is a device that detects any kind of charge. When I say charge, I am referring to an object that has gained or lost electrons, because in order to become charged (positive or negative) electrons must be moved. The most common example that we are used to when it comes to gaining some electrons, is sliding our sock covered feet on a carpeted floor. The shock we feel after touching a metal door knob is electrons jumping from our bodies to the door knob and eventually to ground.

Here is a picture of a typical electroscope:

It is made of two metal leaves attached to a metal ball. These leaves are isolated from air currents, so that any movement is the result of electric charges and not random air fluctuations. If you touch an electroscope with a negatively-charged object, the electrons will flow down into the leaves, where they will accumulate on the leaf edges. This behavior is due to their repulsive nature, and the accumulation on the edges actually is how they are able to experience the least amount of repulsive force. The repulsive force experienced by the leaves will cause them to move apart. When the electroscope is grounded, the leaves will fall together again.

In class I used a balloon and my hair to move some electrons from my hair to the balloon. When I brought the balloon close to the top of the electroscope, the leaves at the bottom repelled. BAM…PHYSICS!

Since my students have been begging me for extra credit since the second day of school, I though this would be a great opportunity to stock up on supplies for my lab. You want extra credit in my class? You build something! So, I had m students make electroscopes for a HW pass or 5 points on any exam grade. I had about 15 students make electroscopes, and they all worked!

The collection of electroscopes on display under my smartboard in the front of the class

I am so incredibly proud of my students who made some awesome electrscopes. It’s obvious the all used the same two youtube videos but they did it!!! I will be using these for labs I do in future years of teaching physics! Saved myself and my school a ton of money on lab supplies while simultaneously enriching my students learning experience outside my classroom =)

I will update this post tomorrow with a video of the electroscope working!

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