Chem Blog Week 25

Over the weekend we were given the task to make an electroscope. An electroscope is a device that is able to measure the amount of charge an object has.

How to Make it

An electroscope model closely replicated to my final product

After going through different prototypes of electroscopes this is the process I found to work best. Crumple a piece of foil into a ball. Roll the smaller piece of foil between your palms to form a long, thin rod shape. Now connect the foil ball to the end of the rod with a thin strip of foil. Make a hole in the middle of the jar lid with a hole punch. Be sure that the hole is large enough for the foil rod to fit through. Slide the rod through the hole in the lid, so the ball sits above the lid, outside the jar, when the top is screwed on. Bend the bottom of the rod so it makes a 90-degree angle. The angle should resemble an uppercase L. Make a narrow strip of foil and fold it in the middle. Fold up each end of the strip to make small flaps. Hang the folded strip of foil on the end of the rod where you formed the L shape. The strip should hang evenly on both sides. Screw the lid tightly on the jar, with the foil rod and flaps inside.

How it Works

When a charged body is brought near the metal knob, both strips acquire a like. As a result, they repel each other and spread apart to form an inverted V. Each dangling sheet of the foil will now have a charge, the two dangling halves of the foil will now seek to repel each other as they have the same charge. The electroscope is then charged. If an oppositely charged body is brought close to the knob, the charge on the strips is neutralized, and they again hang straight down. The strips of foil hang straight down when they are not charged. The charge will transfer to the metal foil. The degree to which the foil flattens itself out is a measure of the amount of charge on the foil which shows the amount of charge on the original object.

 The day of the testing went great. I thought my electroscope stopped working but it was just because the object I was using was harder to charge than something like vinyl. There were different types made but they were all mostly based off the same idea. I did have some trouble actually making the electroscope. My original idea using copper wire didn’t work out because I couldn’t find any copper wire, and even the substitute of a wire hanger for the antennae did not give any results. I did some more research and found the best model to get the best results. This week was fun with our project and I hope that we have another project soon!