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Teaching electricity and electronics at secondary school Jaromír Kekule, Charles University in Prague, Faculty of Mathematics and Physics, Czech Republic Abstract This paper presents the web materials, which can help students for better understanding and easier studying Electricity and Electronics and their use in the regular lessons at secondary school in the Czech Republic. Introduction In the world the modern methods of teaching using computer are developed rapidly in the whole world. I think that physics is especially convenient for teaching with computer because it covers both statical and dynamical processes and things are tightly connected to each other. But in our country there are not many multimedia materials for use on secondary schools. There are not many households connected to Internet and that’s why students cannot study at home on-line. There are some problems with Internet at schools, too. But the situation is improving. Nowadays I am working on development an electronic textbook for teaching secondary-school students on theme electricity and magnetism with an emphasis on electronics and this school year I am testing this textbook experimentally in regular teaching and learning on a secondary school. Creation of electronic materials My web will contain practically all of materials that are necessary for students and teacher for teaching and learning electricity and magnetism. This theme covers whole third form of standard secondary school. The web is divided into 22 “chapters” The most of them are motivated by some semiconductor parts that are interesting but not usually contained in standard textbooks for secondary schools. The compulsory subject matter is given in fact as an explanation to it. The greatest emphasis is put on analysis and explanation of devices, which contain semiconductor parts. The materials in “chapters” are well arranged and most of them have a uniform structure. For example to every semiconductor part there is inscribed an independent page. The first thing on this page is motivation (what is this part good for). Further there is a very brief paragraph with description of the part, then its schematic symbol and text and picture explanation how it works. There is a typical simple electric circuit with the part and detailed information about its practical use with links to pages with practical devices. Experiments that student can make by himself are included in corresponding pages and linked from an independent list of experiments. On the theme of common electricity and magnetism, a special emphasis is put on explanation of function of electrical devices of everyday use and technical devices and on analysis and explanation of some interesting electromagnetic phenomena that we can see in nature (for example a lightning). The Book of problems of electricity and electronics is included. The web contains a lot of links to web pages of manufacturers of semiconductor parts and to further relevant pages with explanation of some phenomena and devices. Every teaching material even the expertly good and detailed one is not very attractive when it is not well arranged. For an extensive web there is very important to have a good navigation in the document. I think that frames are very good for it. The screen is divided into three windows. In the largest one you can see what you want to study. The content of all the web is in the left window and on the upper side there is a content of actual chapter. Besides, hyperlinks are coloured (every colour has specific meaning) and contain a mark for recognize if the hyperlink has been already visited or no. Student can go through the web in the same way as at school (blue hyperlinks), he can go back in the past or forward to the future (green hyperlinks), see and make experiments (brown ones). The material contains hyperlinks to the pages on the Internet with information about great physicists. Methods of explanation For better student’s understanding I use various methods of explanation. The fundament is text complemented by a lot of pictures and photographs. I make an effort that students can comprehend some theme only with help of pictures. Where some dynamic processes are delt a with, there are used Java applets or video. Videos are used for student’s own work, too. Students can test their knowledge by a lot of solved problems, self-tests and homework. Thematical plan And how will the classes look like? At the beginning of school year I motivated students with some interesting problems of electricity and magnetism and especially of electronics, for example the following topics: - power stations – heat, water, wind or nuclear energy, problem of storage of electric energy - electromotor – different types - safety devices on railways – automatic control of traffic, rail circuits, remote control; city public transport – preference of trams on crossroads. Now the students must learn a few fundamental topics. They must have some fundamental knowledge about electric charge and forces existing among charges (Coulomb’s law). Electrostatic induction and polarization are then related to electrostatic forces. The next fundaments are electric field and its intensity, electric work, potential and voltage and electric current (DC and AC). For comprehension, how semiconductors conduct electric current, students must have basic knowledge about crystal structure, Pauli’s principle and energy gaps in materials. Next chapters are in fact explanation of some real devices or problems. Each of them starts with some device, mostly electronic device. (By the way, almost all of modern electric devices are electronic devices.) Students should learn what they need for explaining its function. Then we can discuss about related topics. A list of some topics is below; behind the hyphen there are related topics that students should learn simultaneously. thermometers and exposure meters – thermistor and photoresistor; resistivity of conductors and semiconductors, dependence of resistance on temperature, light, electric field and pressure; superconductivity rectifier – semiconductor of type N and P, diode, rectifying of high frequencies; capacity and capacitor, Zener diode how to make high voltage – multiplier of voltage, acceleration of electrons in picture tube; principle of oscilloscope and TV set; magnetic field, Laplace force, magnetic induction, Lorentz force; electromagnet, electromotor, ampermeter, voltmeter regenerative diode – electromagnetic induction, Faraday’s and Lenz’s law, selfinduction how to make light – bulb, conduction in gas, fluorescent lamp amplifying of current – transistor, phototransistor, diac, FET integrated circuits – operation amplifier, logic circuits; calculator, computer regulation of power – resistance regulation, thyristor regulation radio and TV – electromagnetic oscillator, resonance, AC circuits with R, L, C, impedance, electromagnetic waves (reflection, refraction, interference, polarization); radio receiver, tuning (varicap), modulation and demodulation, microphone and loudspeaker mobile phone, GPS how to make electric voltage and current – cell, accumulator battery, electromotive voltage, Ohm’s law; photodiode, Hall’s phenomenon, alternator, power station, transformer, three-phase voltage electric power – power, energy and work in AC and DC circuits; asynchronous motor how to save information – cassette, floppy disc, hard disc – materials in magnetic field; CD, DVD Use of the web This year I use my in regular teaching on a secondary school. Directly in lessons I want to use pictures and applets, which are for understanding better than words. Students can study at home with the web. For this reason this web is located on the Internet, on school intranet and on student’s home computers. I want to motivate students for making on-line homework. Of course, we will make experiments and laboratory work at school, for example with system ISES (Intelligent School Experimental System, see http://www.ises.info/; it’s a system that can change your computer in oscilloscope, ampermeter, voltmeter, thermometer and many other measure devices), and I want to motivate students for making simple experiments and devices at home (See Fig. 1). Figure 1. A simple electronic device (time switch) – inspiration for student’s own work Conclusion The hypertext material has a great advantage. It can be arranged in more ways, for example by sequence of lessons or similar to paper books. The web can be used offline, too, but for homework and links it will be necessary to have connection to Internet. Every student has this possibility at school. All of students have a computer at home and therefore they can study with offline version. I believe that students will accept this method and their learning will be more pleasant and successful than so far. .