1.1 Methods of Electrostatic Charging PDF
| Title | 1.1 Methods of Electrostatic Charging |
|---|---|
| Course | Electronics Engineering |
| Institution | De La Salle University |
| Pages | 16 |
| File Size | 1.4 MB |
| File Type | |
| Total Downloads | 10 |
| Total Views | 148 |
Summary
you can...
Description
Unit 1: Electric Charge and Coulomb’s Law Lesson 1.1
Methods of Electrostatic Charging
Contents Introduction
1
Learning Objectives
2
Warm Up
2
Learn about It!
3
Electrostatics Electric Charges Interaction of Charges Conductors and Insulators Methods of Charging Structure of the Atom Charging by Friction Charging by Conduction Charging by Induction Conservation of Charge
3 3 4 5 6 6 7 8 9 11
Key Points
11
Check Your Understanding
12
Challenge Yourself
14
Bibliography
15
Unit 1: Electric Charge and Coulomb’s Law
Lesson 1.1
Methods of Electrostatic Charging
Introduction Eating food is the primary process of how we can intake essential vitamins and minerals that are important for differentchemicalprocessesinourbodies. Different elements make up the food that we eat. Elements are made up of atoms, which are then composed of three subatomic particles: protons, neutrons, and electrons. Among these subatomic particles, protons and electrons are charged. The interaction between charged particles explains a lot of phenomena that take place in our everyday life. In this unit, we will be focusing on electrically charged particles and their interactions. In this chapter, we begin our study of electromagnetism by examining the nature of electric charge and how they are transferred from one material to another. 1.1. M ethods of Electrostatic Charging
1
Unit 1: Electric Charge and Coulomb’s Law
Learning Objectives
DepEd Competencies ●
In this lesson, you should be able to do the
induction
following:
●
Describe using a diagram charging by rubbing and charging by (STEM_GP12EMIIIa-1).
Identify the two types of charges:
●
Explain the role of electron transfer in electrostatic charging
positive and negative.
by rubbing
●
Predict charge distributions, and the
resulting
attraction
( STEM_GP12EMIIIa-2).
or
●
repulsion, in a system of charged
(STEM_GP12EMIIIa-3).
insulators and conductors.
●
●
State that there are positive and negative charges, and that charge
Explain how charging by rubbing,
is measured in coulombs
charging by conduction, and
(STEM_GP12EMIIIa-4).
charging by induction takes place.
●
Describe experiments to show electrostatic charging by induction
●
Predict charge distributions, and the resulting attraction or
State the law of conservation of
repulsion, in a system of charged
charge.
insulators and conductors (STEM_GP12EMIIIa-5).
Warm Up
Roll that Can
15 minutes
This activity introduces the nature of charges and how charges are transferred from charged materials.
Materials ●
air pump
●
meter stick
1.1. M ethods of Electrostatic Charging
2
Unit 1: Electric Charge and Coulomb’s Law
●
balloon
●
empty tin can
Procedure 1. Inflate the balloon using an air pump. 2. Group yourselves with an equal number of members. 3. Position yourself with your group members at least three meters apart. 4. Rub the balloon to your hair. Then, use the balloon to move the tin can without touching it. Once you reach the 3-m mark, give the balloon to your groupmate. 5. Continue until you reach the finish line. 6. The first group who finishes wins.
Guide Questions 1. What happens with the balloon as you rub it on your hair? 2. Will the tin can move if you did not rub it on your hair? Why or why not? 3. What do youthinkare the factors that can affect the strength of attraction between the can and the balloon?
Learn about It! Electrostatics The interaction of charges when they are stationary is crucial to understand electricity and magnetism. The study of stationary charges is called electrostatics.
Electric Charges Electric charge is the fundamental property of matter that is carried by elementary particles. B enjamin Franklin, an American physicist, carried out a series of experiments involving flying kites during thunderstorms which led to the discovery of electric charge. He named the charge on a glass rod rubbed with silk as positive electricity. The charge on materials similar to ebonite (a very hard form of rubber) rubbed with animal fur was referred to as n egative. Franklin also discovered that a charged conducting sphere has no electric field inside it since the field and the charges are always outside the sphere. 1.1. M ethods of Electrostatic Charging
3
Unit 1: Electric Charge and Coulomb’s Law
Benjamin Franklin used the notations p ositive a nd n egative t o describe charges. This convention is still adopted until today. In 1897, J .J. Thomson discovered the presence of electrons. Through a series of experiments, it was found out that all electrons present in every atom have the same charge. Rutherford’s experiment showed that atoms also contain protons that have an opposite charge of an electron. By convention, the n egative charge i s assigned to the electron while the p ositive charge i s assigned to the p roton. There are only two types of charges, and materials can acquire thesechargesdependingon the number of protons and electrons present in them. Charges are measured in coulombs o r C.
Interaction of Charges Experiments show that positively charged objects are attracted to negatively charged objects but repelled by any other positively charged object. F igure 1.1.1 summarized these interactions.
Figure 1.1.1. The diagrams show the interaction of (a) opposite and (b) like charges. 1.1. M ethods of Electrostatic Charging
4
Unit 1: Electric Charge and Coulomb’s Law
Why can there still be an attractive force between a neutral object and a charged object?
An attraction between charged and uncharged objects is still possible through charged separation in the uncharged object. In F igure 1.1.2, electrons in the neutral sphere are attracted to the positive sphere (sphere A) and move towards it. The electrons are already closer to the positive charges in sphere A than the fixed positive charges on B. The overall force is towards sphere A as the force between two charges increases with a decrease in distance.
Figure 1.1.2. The diagram shows that there is an attractive interaction between a neutral object and a charged object.
Conductors and Insulators There are two types of materials based on the ability of the object to let electrons move through it. C onductors a re materials that permit the electric charge to move easily from one region of the material to another. On the other hand, i nsulators a re materials that do not let this happen. It can be seen in F igure 1.1.3 that the presence of a charged rod does not affect the arrangement of the charges in an insulator unlike in a conductor. 1.1. M ethods of Electrostatic Charging
5
Unit 1: Electric Charge and Coulomb’s Law
Figure 1.1.3. The diagrams show the effect of a charged rod to an insulator (left) and a conductor (right).
Methods of Charging Structure of the Atom To easily understand different methods of charging, it is vital to have a mental image of the structure of atoms. Atoms are made up of three subatomic particles namely: e lectrons, protons, and neutrons. The first two particles are negatively and positively charged, respectively. Neutrons, on the other hand, are neutral. The protons and neutrons are densely concentrated into a very small point in the atom, making up the n ucleus. The number of protons determines the element’s atomic number of the material. Thus, the number of protons is the fingerprint of the materials. Electrons surround the nucleus. To compare how small the nucleus is, consider an atom to be a few kilometers across. At this enlarged version, its nucleus would be only the size of a tennis ball, and the electrons are several kilometers away from it, as shown in F igure 1.1.4. Electrons can easily jump from one material to another. Thus, electrons are the charge carriers.
1.1. M ethods of Electrostatic Charging
6
Unit 1: Electric Charge and Coulomb’s Law
Charging by Friction Objects are usually electrically neutral or uncharged, but they may become electrically charged when they are rubbed against another material. When one material is rubbed against another, there is friction between them, and electrons may be transferred from one material onto the other. The material that has gained electrons is now negatively charged, and the material that lost electrons is positively charged. Examples of electrostatic experiments can be seen in F igure 1.1.5.
Figure 1.1.5. Diagrams showing experiments in electrostatics. Recall that like charges repel while opposite charges attract.
What type of charge is transferred from one material to another during charging by friction?
1.1. M ethods of Electrostatic Charging
7
Unit 1: Electric Charge and Coulomb’s Law
Between two objects that are being rubbed, how can you determine which will become negatively charged and which will become positively charged?
The t riboelectric series (also called the e lectronegativity scale) ranks materials based on their tendency to acquire charge. These materials are arranged based on their electron affinities. E lectron affinity is a property of a single, unbound atom, and it quantifies the amount of energy released when an electron attachesto the atom. The higher the electron affinity of an object, the greater its tendency to attract electrons. In F igure 1.1.5, plastic has a higher electron affinity than fur and silk than glass. A sample triboelectric series is shown in the figure below.
A sample triboelectric series for select materials.
Charging by Conduction Charging by conduction, also known asc harging by contact, occurs when a charged object is in contact with a neutral object. F igure 1.1.6 shows how an uncharged metal object can 1.1. M ethods of Electrostatic Charging
8
Unit 1: Electric Charge and Coulomb’s Law
be charged by a negatively charged conductor.
Figure 1.1.6. Charging by conduction between a charged and a neutral metal object. Suppose that these two objects are placed on an insulating stand such that they can be easily moved around without being affected by other objects around them. Separation of charges in the neutral object occurs when these two objects are placed close to each other. The electronsarerepelledon the other side away from the negatively charged object. At this point, no charges can be transferred since they are not in contact yet. Once the objects are in contact with each other,someof the negative charges from the negatively charged object will transfer to the uncharged metal object. When the process of charging by conduction is complete, the initially uncharged object now has an excess negative charge. The initially charged object is still negatively charged but has less excess negative charge than before.
Charging by Induction Aside from charging by friction and by conduction, an object can also be charged if they are not in contact. This method is called charging by i nduction. F igure 1.1.7 shows how charging by induction occurs.
1.1. M ethods of Electrostatic Charging
9
Unit 1: Electric Charge and Coulomb’s Law
Figure 1.1.7. The diagram shows the process of how to charge an initial neutral metal sphere through induction. The ball is a conductor because it allows the movement of the charges to take place. The presence of the negative rod makes the positive charges to be induced in the side of the sphere near the rod. The negative rod, on the otherhand, tendsto stay at the opposite side of the rod since negative charges tend to repel each other. When a grounded wire is connected to the sphere, negative charges go directly to Earth, leaving the positive charges behind. As the ground is disconnected and the rod is removed, the sphere is left as positively charged.
Did You Know? Electrical connections in appliances usually have three wires. The first two wires are required connections in an electrical circuit. 1.1. M ethods of Electrostatic Charging
10
Unit 1: Electric Charge and Coulomb’s Law
These are called the “hot wire” and “neutral wire.” The “hot wire” carries the normal voltage to the appliance. The “neutral wire” carries the current returning to the appliance. For a three-pronged plug, the round prong is a wire connected to the ground.
A three-pronged plug.
Conservation of Charge In general, methods of charging follow a the l aw of conservation of charge. It states that the algebraic sum of all the electric charges in any closed system is constant. For example, when you rub a piece of plastic rod with fur, the rod becomes negatively charged, and the fur becomes positively charged. The rod gains negative charge, and the fur acquires the same magnitude of positive charge since it loses electrons. Hence the total electric charge on the two bodies together does not change. In any charging process, t he charge is not created or destroyed; it is merely transferred from one body to another.
K ey Points ___________________________________________________________________________________________ ●
There are two types of charges: positive and negative .
●
Changes in charges are brought by the movement of n egatively charged particles.
1.1. M ethods of Electrostatic Charging
11
Unit 1: Electric Charge and Coulomb’s Law
●
Forces between charges can be either r epulsive or a ttractive. L ike charges attract and unlike charges repel.
●
There are three methods of charging an object: charging by friction, charging by conduction, and charging by induction. ○
Charging by friction can happen when you rub two objects with unequal electron affinity. The object with higher electron affinity acquires the negative charge, while theotherobject with lower electron affinity acquires the positive charge.
○
Charging by conduction occurs when a charged object comes in contact with a neutral object.
○
Charging by induction can happen due to induced charges. The charges in a conducting object can be rearranged with the presence of an external charged object.
___________________________________________________________________________________________
Check Your Understanding A. Write T if the statement is true and F if false. __________ 1. There are three types of charges: positive, negative, and neutral. __________ 2. The only factor that affects the charge of objects when you rub them
is their electron affinity
__________ 3. Charges are not always conserved when you charge an object by
induction.
__________ 4. Protons are the charge carriers. __________ 5. Conductors permit the movement of charges through it. __________ 6. Charging by friction can take place even if two objects are not in
contact with each other.
__________ 7. In a neutral sphere, the number of positive charges is more than the
number of negative charges.
1.1. M ethods of Electrostatic Charging
12
Unit 1: Electric Charge and Coulomb’s Law
__________ 8. Triboelectric series ranks materials based on their electron affinities. __________ 9. The number of protons determines the element of an atom. __________ 10. Protons and neutrons can freely move from one object to another. __________ 11. Charges in a conducting sphere tend to stay at the surface. __________ 12. A grounded wire transfers excess charges to Earth. __________ 13. Unlike charges attract. __________ 14. The algebraic sum of all the electric charges in any closed system is
constant.
__________ 15. Electrons hang out around the nucleus. B. Using the letters A to E, arrange the following steps in charging an object through induction. 1. Attach the metal sphere on an insulating stand.
____
2. Put the rod close to the sphere but not too close for the objects to touch.
____
3. The charges will be rearranged in the sphere.
____
4. Attach a grounded wire to the metal sphere.
____
5. Remove the grounded wire and move the rod away from the metal sphere. ____ C. Draw the charge distribution of the follow...
Similar Free PDFs
Triboelectric Charging
- 2 Pages
Electrostatic series worksheet
- 1 Pages
02 - LAB Electrostatic Series
- 2 Pages
Joint-charging-standards
- 1 Pages
Coin based mobile charging
- 59 Pages
Methods of Formation of Theory
- 4 Pages
Methods of enquiry - hehehe
- 21 Pages
METHODS OF RESEARCH
- 34 Pages
Official Methods of Analysis
- 8 Pages
Methods of sampling aggregates
- 2 Pages
Syllabus of Mathematical Methods
- 1 Pages
Methods of Integration Practice
- 6 Pages
METHODS OF HANDLING DEADLOCK
- 2 Pages
Methods of selection - yeh
- 2 Pages
Popular Institutions
- Tinajero National High School - Annex
- Politeknik Caltex Riau
- Yokohama City University
- SGT University
- University of Al-Qadisiyah
- Divine Word College of Vigan
- Techniek College Rotterdam
- Universidade de Santiago
- Universiti Teknologi MARA Cawangan Johor Kampus Pasir Gudang
- Poltekkes Kemenkes Yogyakarta
- Baguio City National High School
- Colegio san marcos
- preparatoria uno
- Centro de Bachillerato Tecnológico Industrial y de Servicios No. 107
- Dalian Maritime University
- Quang Trung Secondary School
- Colegio Tecnológico en Informática
- Corporación Regional de Educación Superior
- Grupo CEDVA
- Dar Al Uloom University
- Centro de Estudios Preuniversitarios de la Universidad Nacional de Ingeniería
- 上智大学
- Aakash International School, Nuna Majara
- San Felipe Neri Catholic School
- Kang Chiao International School - New Taipei City
- Misamis Occidental National High School
- Institución Educativa Escuela Normal Juan Ladrilleros
- Kolehiyo ng Pantukan
- Batanes State College
- Instituto Continental
- Sekolah Menengah Kejuruan Kesehatan Kaltara (Tarakan)
- Colegio de La Inmaculada Concepcion - Cebu