JapanJapanSocietyfor Society for Science Education 169 Research Article DEVELOPMENT OF HANDS-ON EXPERIMENT EQUIPMENT FOR OBSERVING STATIC ELECTRICITY BY MAKING USE OF PLASTIC BOTTLES Tomoya YUNOKI . Kishiwada Municipai Orniya Elementary School ABSTRACT ' The purpose of this study is to enhance the instruction of static electricity through the use ef plastic bottles, By utilizing cheap plastic bottles, we can make the experiment instrument cheaply and convenienuly. The equipments used ior producing and observing static electricity are electrostatic generators, electrostatic motors, and Ieaf electroscopes. This study will demonstrate how it is possible for each student to construct these necessary materials with plastic bottles, In particular, the Kelyin electrostatic generator made with plastic bottles reveals a surprising phenomenon to the students. Plastic bottles are usefu1 for demonstrating and learning about static electricity and energy. Various experiments can be conducted using plastic bottles and they are instrumental in stirring an interest in the students, Key words: electrostatic motor, energy education, Kelvin electrostatic generator, leaf electroscope, static elec- tricity INTRODUCTION An effective way for students to learn about static electricity is to have them conduct their own experiments and to also have them produce their own equipment. It is necessary that these equipments can be made cheaply and conveniently. By utilizing cheap plastic bottles, we can make the experiment instrument in the individual and carry out the individual experiment. Stuclents made the foIIowing equipments: 1, Kelvin e]ectrostatic generator 2. Electrostatic motor 3, Leaf electroscope There has been a quantitative consideration of the Kelvin electrostatic generator as a teaching tool, (Wakishima and Onizuka, 1994), and there has been some research on the mechanism of the Kelvin electro- static generator (Saito et al, 2003), In this paper, I show that the Kelvin electrostatic generator can be rnade sim- ply and cheaply with plastic bottles. In addition, by using coil, it is possible to observe a wonderful phenomenon: the electrostatic generator reveals that a charged particle can be bent by a force in the electric field. The electrostatic motor and the leaf electroscope are teaching materials that are usually bought or selfimade. These materials, like the Kelvin electrostatie generator, can be made simply and cheaply with plastic bottles, It is possible for each student to make and experiment with all three of these devices. The Kelvin electrostatic generator, the electrostatic motor, and the leaf electroscope rnay be used independently of eaeh other. NII-Electronic Library Service JapanJapanSocietyfor Society for Science Education ' 170 However, combining these mechanisms and using them together allows for a more dynamic lesson with regard to energy education. MATERIALS ANDMETHODS 1.ElectrostaticGenerator a MechanismofelectrostaticgeneratorbyKelvin The Kelvin electrostatic generator was invented by Kelvin U, J. Thomson) of Britain in 1859, Figure 1 shows the basic structure. Water saved in a tank T runs frorn nozzles Nl and N2 as a stream (liquid column). Inductors Il and I2 are put in the vicinity where the streams change into drops of water. These inductors are crossed with- out touching and connected with the water receiving cups Ci and C2. Ci and C2 are mutually insulated well. (D ff Ci becomes positively charged for some reason, I2 connected with Ci becomes positively charged. @ A negative charge is induced in the stream from nozzle N2. @ When the stream divides into drops, the negative charge is preserved, fa11s and collects in C2. @ When C2 becornes negatively charged, Il connected with C2 becomes negatively charged, @ A positive charge is induced to the stream from nozzle Nl, @ When the stream is divided into drops, the positive charge is preserved, fa11s, and collects in Cl. - Thus, the charges collected in Cl and C2 grow, and their potential increase while repetition (D @. A high voltage of 10-20kV can be generated even though this device is such a simple structure (Ueda et al, 1991). b Procluctionofelectrostaticgenerator (D Items required Plastic bottle (large) One (2000ml or 900ml with a cap) Plastic bottle (small) Two (500ml with a cap) Enamel coated copper wire Two (O.5rnm in diameter, about O.6m in length) Wire (for attaching bottles) One (2mm in diameter, about O.7m in Iength) Nozzle Two (made ofathin glass tube) @ Production (a) The plastic bottle (small) is cut into two parts, and the tank and the water receiving cups are made (Figure 2a). Two pairs are made. (b)Aglass tube of about 4mm in diameter is tapered, and two T nozzles of about 20-30min in length and abouli lmm in diameter at tip are rngde. Next, two nozzles are fixed into holes made in the caps of two plastic bottles, This rnakes N2 two nozzles (Figure 2b). (c) A coil is made by wrapping a length of enamel coated Il I2 copper wire around an AA baitery several times, Then peel off the coating for about 20mm from the wire ends. Make two of these to be used as inductors (Figure 2c), C C2 (d) The two tanks are attached to the plastic bottle (large) with a wire. Next, the two inductors are fixed to the plastic bottle so that the center of each coil is aligned directly Figure 1. The structure of Kelvin electro- under each nozzle, and so that the bare end touches staticgenerator NII-Electronic Library Service JapanJapanSocietyfor Society for Science Education 171 d Fix a wire to a cap b 'WrapaaTound aTound concave part a Tank Tank le -----.Water-rec c Water-receiving cup --- li'..---PPIl,'"v.----- il Water-receiving CLIP Peel the film Fix a wire with an adhesive tape Figure 2, (a) Cutting ofplastic bottles (b) Cap of plastic bottle (c) Inductor (d) Assembly figure of the elee- ' trostatlc generator inside the bottom of the water-receiving cup on the ether side of the large bottle. At thi$ time, two inductors are set so that they can part mutually (Figure 2d). @ Note for use Water is poured into two upper tanks. Be carefu1 to keep the two sides balanced, Then the water in the two tanks is connected with an aluminum foil strip or some other type of conductive material etc., and the potential is made to be equal. Moreover, the coils are adjusted so that the strearn of water that drops frem the nozzle can pass through the center of each coil (Figure 3). Electricity is used by connecting leads to the inductive wires touching the water, respectively, c Characteristics of the electrostatic generator The performance of the electrostatic generator has much to do with the state of insulation, and, as well, its performance fails if a short circuit occurs. When the voltage between the two poles of this generator (water in the water receiving cups) was measured with an electrostatic voltmeter, the voltage was 9-10kV. Because this generator was a symmetric structure, it is thought that the electrical charge in each water- receiving cup is decided by chance. However, the amount of electricity increases if a kind of electrical charge is set by some source first, so the electrode can be decided if the electrical charge is established (for example by friction) beforehand, In the that was this electrostatic generator produced 3. Static electricity generator under power ' time, the tank was separated. In this･separation type, ifFigure generatlon NII-Electronic LibraryMbrary Service JapanJapanSocietyfor Society for Science Education 172 a b Figure 4. (a) Dancing water drop]et (b) Water droplet after l130th second of Figure 4 (a) the water in the top tanks is not connected with alumi- num foil, electricity with an opposite charge to that in the respective water-receiving cup collects in each tank. This can be confirmed in the case of the leaf electroscope that fo11ows in this paper, and with neon tubes, etc., and is usefu1 in confirming the mechanism of power generation. When we carefu11y observe the state of the water droplet, we can notice the change of the water droplet. This phenomenon can be observed when the voltage Figure 5, The water clroplet'which is distributed in rises. Therefore, we can guess the voltage from the the circumference of the equipment aspect of the water dreplet. By the electric field in the coil, the stream of water is divided into small water droplet, In addition, some water droplet do wonderful movements (Figure 4a, Figure 4b) . Figure 4b is a picture after 1!30th second oi Figure 4a. We can observe the aspect in which srnall water dreplet flies over the circum- ference of the coil. Also the water droplet is dispersed in the circumference of the equipment (Figure 5). Such phenomena are observed because the water clroplet which has electricity is moved by the force of the electric field, 2. Electrostatic Motor a Mechanismofelectrestaticrnotor Figure 6 shows the basic structure of the electrostatic motor which is to be preduced. The rotator can turn around O, and there are parts (henceforth part I) where aluminum foil is attached. Pole A and Pole B being made of aluminum foil, they are flexible so they can move a litule and can touch Part I. Pole B is grounded, androuches , the rotator lightly, (D As is shown in Figure 6a, when Pole A becomes positively charged, a negative charge is induced to Part Il near Pole A. An electric field caused between Part Il and Pole A makes the rotator rotate clockwise. NII-Electronic Library Service JapanJapanSocietyfor Society for Science Education 173 a b + + Pole A PoleA ++ Polc A + + I, Rotator I, Insulator a l eL+ J PoleB PoleB c + Pole A d Pole A +++ rtI ++ t+ Pole B(Ground) a+ tL+ +J J +tLe ++ PoleB PoleB Figure 6. The structure of electrostatic motor from above @ As is shown in Figure 6b, when attraction makes Pole A touch Part Il, a positive charge moves to Part Il, @ When a positive charge rnoves to Part Il, repulsion works between Pole A and Part Il, and Pole A moves away from the rotator, and Part Ii which has become positively chargecl, receives power from Pole A.