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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.
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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 diameterat tipare rngde. Next,two nozzles are fixedinto
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
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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.----- Water-receiving il 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
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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.
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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.
On the other hand, a negative charge is induced on the following Part I2, and an attractive function between Part I2 and Pole A, The attraction makes the rotator rotate further clockwise. Thus, as in Figure 6c, a positive charge repeatedly moves to part I. @ As in Figure 6d, Part Il, which has become positive, comes in contact with Pole B, which is grounded, ancl
loses its charge.
The above is repeated; therefore, a pesitive charge is carried from Pole A to Pole B, which is grounded.
At this time, in the case that Pole B has become negatiyely charged, the phenemenon that occurred in Pole
A occurs similarly in Pole B. As a result, the rotator rotates quickly. In this case, both the positive charge in Pole A ancl the negative charge in Pole B gradually decrease. The alu-
minum foil on the pole might not need to touch the rotator depending on the amount of voltage.
b Productionofelectrostaticmotor
Q Items required Plastic bottle (small) One (round type 500ml)
Plastic bottle (large) One (round type 1.51)
Cap of film case One (hellow in center) Bamboo skewer One (About 150mm in length)
Aluminum foil One (about lOOmmxlOOmm) @ Production (a) A rotator is cut from the bottle (small), and the base is cut off from the bettle (large) (Figure 7a). fo) Aluminum foil pieces of 10mm width and 25mm length are attached to the rotator at 5mm intervals in order
to rnake Part I. The cap of a film case is attached upside down to the small bottle's mouth (Figure 7b).
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c Figure from al)ove
a bCap of film case
Rotatoror Alumm end und
--B Base
Aluminum foil(Part I)
Figure 7.(a) Cutting ofplastic bottles Cb) Rotator (c) The base of electrostatic motor
(c) The bamboo skewer is pierced up through the center of the bottom of the base bottle, The electric poles are made by using two strips of aluminum foil, the poles are set to the
base bottle, and at this time, the tip of each pole is cut round so that friction may decrease. Moreover, sections from
the sides of the plastic bottle (base part) are cut out so that each pole does not touch the bottle's surface (Figure 7c). (d) The rotator is put on the tip of the bamboo skewer (Figure 8). @ Note for use
Pay attention that there is no dirt on the rotator, etc.
c Characteristics of the electrostatic motor
The electrostatic motor that is produced here needs about 3kV to begin to rotaLe when one pole is grounded and the other pole is connected to the pole of the electrostatic generator;
the rotation Figure 8. Plastic bottle type electrostatic stops when voltage dropsbelow2,6kV. motor It begins to rotate at about 2kV when the two poles connect to the electrostatic generator.
Paper foil can be used for Part I and of electrostatic motor case, a voltage thepoles , butinthat higher (about
6kV) is necessary.
3.LeafElectroscope
a Mechanismofleafelectroscope
A leaf electroscope was made by Bennet (A, BenneO in Britain in 1787. Figure 9 shows the basic structure of a leaf electroscope. When an electrical charge is given to a conductor,
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foils become homogeneously charged and epen by repulsion. ++ According to the angle at which the foils open, the quantity otor of electricity can be determined.
s b(DProduction of leaf electroscope Items required l Plastic bottle One (1.51-21 with a cap)
Aluminum foil One (about 200mm x 200mm)
Straw One (about 6mm × 100rnm in diameter) Figure 9. The structure of leaf electroscope
CorrugatedcardboardOne (about 50mm × 50mm) Thin Japanese paper Two (about 40mmx4mm) @ Production (a) The plastic bottle is cut so that the top part and base part can be used without the long middle barrel. A case is then made by putting the top and base together (Figure 10a).
The plastic is only partially able to retain static electricity. Therefore to get better conductivity in the case,
a liquid of diluted hair shampoo rinse should be painted on the case. (b) Aluminum foil of about 150mm in length is folded several times to create a rigid strip about 4mm wide. The upper ends of twe pieces of thinJapanese paper (size is 40mm × 4mm) are glued onto this foil strip, A round
piece of corrugated cardboard (about 50mm in diameter), a straw (about 100mm in length), the cap of a
plastic bottle, and the aluminum foil strip with the Japanese paper glued to it are assembled as shown in Fig-
ure 10b, Following this, the corrugated cardboard is wrapped with aluminum foil. At this point, the main part of the leaf electroscope has been completed.
bCoirugatedcardboard
wrapped with Numinum foil
C
a
l strip
------sivetape
e paper
--- ->
Figure 10, (a) Production efacase (b) The inside of the leaf electroscope
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(c) Encase this main part in the bottle parts (Figure 11).@
Note for use
A leaf electroscope can be used to determine the
type of electric charge. This is because the leaves
haye been insulated from the circumference. In this
case, in order to examine the type of electric charge, the static electricity for which the type of electric charge has been proven must be charged.
For instance, if the foil has a negative charge of
electricity, the leaves shut when a positive charge of
electricity is brought close to the leaf electroscope,
and open further when a negative charge of electricity
is brought close. The electrical charge can be deter-
mined from what has been stated above.
C Characteristicsof theleafelectroscope Figure 11. Plastic bottle type leaf electroscope Tissue paper and toilet paper can be used as paper glued to the foil. However, because they become easily deformed while being used, thin strong Japanese paper is recom- mended.
The opening angle of paper leaves depends on the thickness and size of the Japanese paper used, The leaf electroscope which is preduced here opens to an angle of about 20e at lkV, and to the angle of 600 at 3kV. Xlhen paper leaves were replaced with silver fbil of about lpm in thickness, they opened to abeut 800 at lkV, Among leaf electroscopes on the market, there are some which open to about 120e or more at lkV, Japanese
paper is inferior to metallic foils in terms of sensitivity. However, Japanese paper is practical enough use when various experiments about static electricity are done. On the other hand, in the case of metallic foils, production is dithcult, and much attention must be paid to handling them, Considering these facts, Japanese paper was used this.time.
4. Regarding the Use of the Devices as Tbaching Tools In the Science subiect in the Course of Study at junior high schools, static electricity is taken up as an "Current "The introduction of and Its Use". Students are asked to find out power which works at a distance and the relationship between static electricity and current" (The Ministry of Education, 1998), "Electricity Moreover, static electricity is taken up as an introduction in study concerning and Magnetism" in high schools (The Ministry of Education, 1999),
Because the electrostatic generator can procluce stable static electricity, the range of its application is wide.
Fer example, it can be used to make a fluorescent lamp and a neon tube shine, as is shown in Figure 12. This is
an example of the conversion from electric energy to light energy. Moreover, various experiments and demonstrations regarding static electricity can be conducted (for example
Donald, 1972;Joe, 1982).
By combining the use of these experirnent devices, static electricity produced by the electrostatic generator is confirmed with the leaf electroscope and can make the electrostatic motor rotate (Figure 13). This is an
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./it/v.'
Figure 12. The lighting of the fiuorescent lamp Figure 13. The combination of the e>rperiment
teaching material (Kelvin electrostatic generator, electrostatic motor, leaf electroscope)
example of the conversion from electric energy to kinetic energy,
At this time, the papers of leaf electroscepe close as the electrostatic motor rotates, and they close faster as the motor rotates faster.
Because the quantity of generated electricity is small in the experiments using these devices, there is no
particular danger under normal conditions, as long as it is not saved in an external deyice such as Leyden bettles,
However, it is necessary to conduct experiments carefu11y in accordance with the different situations,
CONCLUSION
Appealing to students with fun experirnents stimulates their natural inquisitiveness. Observing the move-
ments of charged particles in the electric field and experimenting with energy conversion are interesting ways
for students to learn about static electricity and energy, respectively.
The construction of the equipment is valuable in itself, The value of these devices lies in the fact that each
student is able to produce their own scientific equipment and that he can experiment with these devices, E]rper-
iments and ebservations are important but it seems still more effectiye that students experirnent with and
observe static electricity and energy through equiprnent of their own making.
Performing interesting experiments by using familiar materials becomes eyen more important in the future
to promote and encourage each student's scientific curiosity.
REFERENCES
Donald, J. P.: Electrostatic Lobby Display, 7]he Physics 11eacher 10, 100-101, 1972.
"Ting-a-Ling" Joe, P.: The Machine, IVze Ilhysics Teacher 26, 304-306, 1988.
Saito, Y., Nishio, K., Yoshimoto, N. and Kaito, C.: Suitekihatsudenki-no Mechanism (Mechanism of Kelvin
Electrostatic Generator), foumeal of the Rleorsics Education Sociely ofLtctpan 51, 187-192, 2003 (inJapanese). Tamamushi, B. (ecl.): Rikagakajiten (The dictionary of physics and chemistry), Iwanarni Syoten, 423, 1981 (in Japanese). The Ministry of Education: The Course of Study of junior high schools, 46, 1998 (in Japanese),
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The Ministry of Education: Explanation of The Course of Study of senior high schools (science and mathematics), 79, 1999 (in Japanese),
The Ministry of Education, Culture, Sports, Science and Technology: Guidance material on the teaching in
propertion to the individual Uunior high school, science edition), Kyouiku Shuppan, 121-128, 2002 (in Japanese). Ueda, M. (ecl,): Seidenki-noJiten (The dictionary of static electrdication), Asakura Syoten, 78, 1991 (inJapanese). Wakishima, O, and Onizuka, S,: Kelvin Electrostatic Generator a Teaching Material, fournal of the Rhysics Education Society qfl`tpan 42, 419-422, 1994 (in Japanese). ,
Yunoki, T.: The Development of the Teaching Materials on Static Electricity by Using Plastic Bottles., Osaha
and Science Education 15, 5-8, 2001 (in Japanese). (Received December 11, 2006; Accepted March 19, 2007)
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