Project 1: Electroscope Stephanie Mae M. Torcatos1, Jamella Atiga, Atiga, Rose Ann Mangantang, Chyril Chyril Narvasa, Lorie Sodusta, Aira Valeros Department of Senior High School, Science and Technology Engineering and Mathematics, Polytechnic University of the Philippines, Sta. Mesa, Manila 1016 1
E-mail:
[email protected]
Abstract. This experiment aims to demonstrate electrostatics by making electroscope. Different materials such as ballpen cap, marker, comb, ruler, plastic cover, and electroscope were used. Different methods of charging were used to charge the objects. As the time of charging increases, the magnitude also increases. As the magnitude increases and the distance decreases, the attraction or repulsion increases. This shows the Coulomb’s law.
Keywords: Keywords: Electrostatics PACS: 41.20.Cv
1. Introduction
Electricity is not always at motion. When it is at rest, it is known as an electrostatic charge. According to Ricky (2008), an electrostatic charge cannot flow on insulators for it has low electron mobility which means it has few or no free electrons. [1] There are two types of electric charges which are positive charge and negative charge. Electric charge, which can be positive or negative, occurs in discrete natural units and is neither created nor destroyed according to Law of Conservation. The SI unit for charge is coulomb (C). [2] According to the 1st law of electrostatic, like charges repels. Positive repel positive and negative repels negative for they have the same polarity. And the 2nd is that unlike charges attract. According to this law, the force exerted between two point charges is directly proportional to the product of their strengths. [2] There are different methods of charging. First is charging by Friction. With this method, this process results in a transfer of electrons between the two objects that are rubbed together. As a result, the atoms of 1st object pull electrons from the atoms of the 2nd object, leaving both objects with an imbalance of charge.
Another is in the process of Induction. It is a method used to charge an object without actually touching the object to any other charged object In addition to, the 3rd method of charging is by Conduction. Charging by conduction involves the contact of a charged object to a neutral object. Lastly, Grounding is the process of removing the excess charge on an object by means of the transfer of electrons between it and another object of substantial size. When a charged object is grounded, the excess charge is balanced by the transfer of electrons between the charged object and a ground. A ground is simply an object that serves as a seemingly infinite reservoir of electrons; the ground is capable of transferring electrons to or receiving electrons from a charged object in order to neutralize that object. [3]
Coulomb's law states that the electrical force between two charged objects is directly proportional to the product of the quantity of charge on the objects and inversely proportional to the square of the separation distance between the two objects. [3]In equation form, Coulomb's law can be stated as
F=
∙ ∙ 2 2
(1.1)
In this experiment, by creating an electroscope and using different materials, electrostatics can be demonstrated. 2. Methodology
In this project, the group used the following materials to create electroscope and demonstrate electrostatics.
a.
b.
c.
Figure 1.1: (a) Copper wire (b) Foil and (c) Plastic Bottle
To make this experiment possible the group used plastic bottle, aluminium foil, copper wire to make electroscope
a.
b.
c.
d.
e.
f.
Figure 1.2: (a) ballpen cap (b) Paper (c) Ruler (d) Marker (e) Plastic Cover and (f) Comb
The group used different materials such as ballpen cap, marker, comb, ruler, and plastic cover to test the electroscope. 3. Results and Discussions
As the group conducted the experiment, each was thrilled with excitement and enjoyment as different objects were rub to each other’s hairs and maong pants just to create charge. Although it’s hard to rub an object for seconds and failed to charge many times, for the group this was the challenge to overcome in the experiment.
Figure 1.3: Electroscope
Figure 1.3 shows the electroscope accomplished by the group. Where in plastic bottle, solid copper wire, and foils were used. Table 1.3: Electroscope Materials a. ballpen cap b. marker c. comb (plastic) d. ruler e. plastic
15 seconds Split Split Split
30 seconds Split Split Split Split
45 seconds Split Split Split Split
Table 1.3 shows whether the foil in the electroscope had split using the following the materials in increasing time of charging. In this part of experiment, grounding was also used. From the table, by using a ballpen cap, no splitting happened. By using a marker, in 15 seconds the foil did not split. But as it was charged for 30 seconds and 45 seconds, the foil had split. The comb, ruler and plastic made the foil split as it place nearer the electroscope. And as the time of charging increases the split of the foil also increases.
4. Summary and Conclusion This experiment aims to demonstrate electrostatic by using an electroscope and different materials. By using different methods of charging the different object demonstrates different behaviour. In all the activities done, Coulomb’s second law was applied wherein the attraction and repulsion of objects depends on its magnitude and distance. As the magnitude of charges increases the attraction or repulsion also increases wherein it shows direct proportionality. On the other hand, as the distance increases the attraction or repulsion decreases wherein it shows inverse proportionality to each other. Negatively charged objects brought near the electroscope attract its positive charges bringing down the negative charges thus making the foil both negatively charged and split.
Acknowledgement
The entire group would like to acknowledge with their heartfelt thanks and profound gratitude the following persons whom without their sincere help and guidance will not make this report possible. Mr. Reynold V. Luna, our General Physics I instructor, who impart his knowledge to us and gave all the details, information and instructions to make this project successful. To the Javier Family, who gives guidance and all-out support along the process of creating these projects. Also, for letting us stay in their home to finish all of these. To all those who, may be in any form or aspect, have helped make this experiment a reality. Above all, to God be the glory always. References
[1]
[2] [3]
Ricky(2008), "Electricity at Rest - Electrostatic", retrieved at http://www.brighthubengineering.com/power-generation-distribution/3014-electricity-atrest-electrostatic/ "The editors of encyclopedia Britannica, Electric charge", retrieved at https://www.britannica.com/science/electric-charge "Static Electicity - Lesson 2 - Methods of charging", retrieved at http://www.physicsclassroom.com/class/estatics/Lesson-2/Grounding-the-Removal-of-aCharge
