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Home-made electric current sources

This is physics project proposed by Anca Adriana Arbune, a 17-years-old maths student at the “Vasile Alecsandri” National High School in Galatzi Romania. She presents some proposals to create home-made electric current sources to explore and experiment the world of Physics.

Information about materials to be used and scientific explanations are also provided.

This project has been presented in the regional phase of the physics contest "Stefan Procopiu" in Romania and has been awarded with two diplomas, one the "Edison Diploma", for scientific creativity and the second, the "Jules Verne" for anticipative scientific imagination.

1) How to create an organic battery
Used materials: a grapefruit, a copper plate, a zinc plate, a consumer or a voltmeter.

The grapefruit is firmly pressed, without peeling it. The plates must be polished with sandpaper in order to remove the oxides from the surface. These plates are introduced into the grapefruit, the copper plate on one side and the zinc one on the other, without connecting the two, at a distance of about 1-2 centimeters one from the other. Then, the plates are connected to the consumer using terminals (the zinc plate is the negative coil, and the copper plate is the positive one) and you will notice that the grapefruit produces electrical power). Download the complete organic battery activity (pdf. English) with explanations and suggestions.

2) The electrochemical battery
Used materials: copper plate, a zinc plate, a solution of copper sulphate, a solution of zinc chloride, sandpaper, a salt, water, 2 Berzelius glasses of the same height, a “U”-shaped wand, cotton, a consumer and a voltmeter.

The solutions of copper sulphate and of zinc chloride have to be put in the Berzelius glass, separately. The plates must be well polished with sandpaper in order to remove the oxides. The “U”-shaped wand is filled with salt, which has been dissolved in water before, then the ends are blocked with cotton. The copper plate is introduced in the glass that contains copper sulphate, and the zinc plate goes into the glass with zinc chloride, and the “U”-shaped wand is introduced by each end in a glass. Finally, the consumer or voltmeter is connected to the both plates (the positive coil = the copper plate, and the negative coil = the zinc plate). Download the complete electrochemical battery activity (pdf. English) with explanations and suggestions.

3) How to prepare a solar cell
Used materials: 4 copper thin layers of 30X30 sq cm, a scissor for cutting the copper layers, a highly pressurized gas bulb, a CD carcass, kitchen salt, water, a big dropper, sandpaper, silicon glue, 8 wires if copper.

Firstly, a plate of coppery oxide has to be produced. One must cut a piece of the copper plate which is almost the size of the burner. The hands have to be washed so that no trace of oil remains on them. The copper plate must be washed completely with sandpaper or a clearing substance so that any sulphure or another corrosive are eliminated. There, the cleaned copper plate must be put on the burner and the latter must be turned on at its full capacity. When it becomes hot, the copper is covered with a black layer of oxide. This is not the needed oxide, but it will exfoliate later, surfacing the oxide layer of red, orange or purple coloured copper. Download the complete solar cell activity (pdf. English) with explanations and suggestions.

These power sources aren’t as practical as the daily used batteries or the accumulators, but in some conditions they can be useful. This is a list with the possible utilities of the sources:
-turning on a led;
-turning on a bulb;
-verifying the work(ing) of a loudspeaker;
-supplying a digital watch;
-supplying the blitz of a camera;
-supplying a remote control;
-supplying a pocket laser;
-supplying a stand-by lamp;
-detecting light.

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