O příspěvku
Electrostatics for Children
Abstract
Performing scientific experiments for children is an interesting and important part of stimulating their development. There are presented several experiments with electrostatics in this article. They are easy to carry out and can be done with commonly available materials.
Introduction
In Wroclaw University of Technology we run a kind of university for children called Academy for young Explorers. We organize series of scientific lectures for children. During the meetings we present various problems concerning physics, mathematics, technology etc. We would like to make children fascinated by natural sciences. We do a lot of experiments and children can take part in them. Some children repeat the activities with their parents at home. The meetings take place at the Institute of Physics [1].
Children love "scientific experiments" that they can do by themselves. For children doing experiments is the natural way of learning about the world. This form of activity often leads to increased interest in science.
The interesting phenomena which children often meet in their lives are connected with electrostatics. The young ones can make an interesting observation while brushing hair, taking off their sweaters, stroking a cat etc.
The experiments with the electrification of objects were already carried out around 600 BC by the Greek scientist Thales of Miletus. He noted that rubbed amber attracted small objects (such as feathers, small straws, etc.). Amber in Greek means “an electron”, so the phenomenon is called “electrification” [2]. In the seventeenth century a similar study on the electrification of objects was performed by the English physicist William Gilbert. He was the one who introduced the word "electricity".
Experiments for Children
I will present here some experiments related to electrostatics which I showed during the Academy for Young Explorers.
A Rolling Can
For this experiment we need an empty metal can of beverage (eg. Coca-Cola, Pepsi or other beverage) and a plastic ruler or a plastic comb. We put the can on the table or on the floor. Then we rub the ruler (or the comb) with a piece of woolen cloth or other material that easily electrifies plastic. After that we bring the ruler close to the can at a distance of about 0.5 cm. The can begins to roll towards the ruler. When we move the ruler, the can is following it. Do not touch the can with the ruler!
Pencil and Ruler Experiments
For this experiment we will need a long wooden pencil with graphite inside. We put it on the narrow block or a bottle cap. Firstly we electrify the ruler as in the previous experiment, and then move it close to the end of the pencil at the distance of about 0.5 cm. The pencil will follow the ruler and turn around, when we move the ruler around the block.
Educational Game "Cinderella"
We scatter a small amount of sugar and rice on a plate then mix these substances. The mixed substances can be separated with the use of electrostatic interactions. To do this you need to electrify the ruler (a straw or a plastic tube) and bring it close to the mixture. Some sugar will be attracted to the ruler.
The Experiment with the Dancing Snake
For this experiment a thin smooth tissue is needed from which we can cut out a small spiral snake. We put it on the table. Then we electrify the ruler and move it close to the head of the snake. If the ruler is electrified then the head of the snake will lift up and cling to the ruler.
Water and Balloon Experiment
For this experiment we will turn on the tap in the bath or in the sink. Water must flow in a very narrow stream. We put an electrified balloon close to the stream of water. The stream of water will be deviated from the vertical run.
Educational Game with a Plastic Bag
It is very easy to electrify plastic bags. We put a plastic bag on the table and we stroke the bag with a dry hand several times. The plastic bag will stick to the table, wardrobe or door. If we take two equally electrified bags and we put them close to each then the bags will repel each other. They are electrified with the same electric charge.
Summary
Simple electrostatic experiments give children a lot of pleasure. They are fun, easy and not very expensive and although they can be done with commonly available materials, they produce spectacular results.
Literatura
[1] http://www.amo.if.pwr.wroc.pl/
[2] HALLIDAY D. R. RESNICK R., Walker J.: Fundamentals of Physics. PWN, Warszawa 2003