Conceptual Physics Electrostatics and Static Electricity Notes and Worksheets

Transcription

1 Conceptual Physics Electrostatics and Static Electricity Notes and Worksheets Electrostatics is the study of electrical charges at rest. Charge is the fundamental aspect of all electrical phenomena. Electrical charge is a property of matter. What this means is All objects are composed of atoms. Atoms contain charged particles: Charge can not be separated from an electron or proton. Electrons (not protons) are prone to move. Electrons are the mobile charge carriers. The process of an electron leaving one object to reside (perhaps only temporarily) in another object is a common occurrence. When this occurs, the object is said to be electrically charged. Static Electricity is caused by an excess of charged particles on an object. Charged Versus Uncharged Objects: Positively-Charged Possesses fewer electrons than protons Negatively-Charged Possesses more electrons than protons Uncharged Possesses equal numbers of electrons and protons (neutral)

2 Law of Conservation of Electric Charge Charge is conserved. It is transferred, not created, nor destroyed. The net amount of electric charge produced in any process is zero. If one region or object acquires a positive charge, then an equal amount of negative charge will be found in neighboring regions or objects. What this means is... The Law of Interactions Between Charges When charged objects come near other objects they will interact. This means that. How do charged objects interact with other charged objects? Like Charges? Opposite Charges? How do neutral objects interact with charged objects? neutral and positive? neutral and negative? Explain how the electrons shift in the neutral object so that there is a force of attraction between the neutral and charged objects. If there is no interaction between two objects, what does this mean about their charge?

3 Why did some objects become charged on the lab, while others did not? Conductors Insulators Kinds of conductors Kinds of insulators How can you determine if an object is charged? Electroscopes:

4 How do objects become charged? Work is done Friction Conduction - Discharging/grounding Induction- Induction Polarize and ground Induction Polarize and separate

5 Charge - the underlying cause of all electrostatic phenomena and electricity Quantity Variable Unit and Unit Symbol Charge - a characteristic of electrons and protons that causes them to interact with each other. (attract / repel) An elementary charge is the smallest particle of matter that carries charge. There are two types of elementary charges. They are... Kind of Elementary Particle Amount of Charge it Carries A Coulomb of charge is a large amount of charge. An object must have a lot of excess electrons or protons to have that much charge. How many electrons (or protons) in one Coulomb of charge? The charge on an object (q) is equal to the number of excess elementary charges times the charge on one elementary charge. q = # of excess elementary charges x 1.6 x C What happens when charged objects touch other objects? Charge can transfer from one object to the other. The rule is...

6 Name: Electrostatics Worksheet #1 Conceptual Physics 1. Describe the charge distribution for an object that is electrically positive electrically negative electrically neutral 2. Draw the charge distribution on the objects below. Include at least 8 charges. Electrically positive electrically negative electrically neutral 3. What will occur if you bring a negatively charged rubber rod near each of the charged spheres? Indicate the interaction between the spheres and the rod (attract or repel). Electrically positive electrically negative electrically neutral What will occur if you bring a positively charged glass rod near each of the charged spheres? Indicate the interaction between the spheres and the rod (attract or repel). Electrically positive electrically negative electrically neutral

7 Electrostatics Worksheet #1 (continued) 5. Describe polarization of charge on a neutral object. Draw the charge distribution on the spheres as a negatively charged rubber rod or a positively charged glass rod are brought near the neutral sphere. Draw at least 8 charges on the spheres. electrically neutral sphere electrically neutral sphere The charges on a polarized object 6. Describe two ways of charging objects by touching them together. What is the difference between the two methods? 7. Draw the movement of charges as a neutral conducting sphere is charge by conduction with a negatively charged rubber rod. Include at least 8 charges on the sphere. Before During After Describe induction (charging objects that involves no contact between the charged object and object being charged). 9. What is a conductor? Why is metal a good conductor? 10. What is an insulator? What kinds of substances are good insulators?

8 Name Conceptual Physics Electrostatics Worksheet #2 1. How do protons and electrons differ in their electrical charge? 2. If an atom (or object) is neutral, how many electrons are there compared to the number of protons? 3. Explain in terms of comparative numbers of protons and electrons why an object has a negative charge? A positive charge? Draw a diagram of a positively charged object and a negatively charged object. 4. How do like charges behave toward each other? 5. How do unlike charges behave toward each other? 6. How do neutral objects behave toward charged objects? What is happening? 7. What does it mean to say that an object is electrically polarized? Draw a diagram of a electrically polarized conducting sphere near a positively charged glass rod. 8. What does it mean to say that charge is conserved?

9 Electrostatics Worksheet #2 (continued) 9. What is an elementary charge? What are the two kinds of elementary charges? 10. What unit is used to measure electrical charge? 11. How much electrical charge does an electron carry? (in Coulombs) 12. How much electrical charge does a proton carry? (in Coulombs) 13. How many elementary charges are in one Coulomb of charge? 14. What is the charge in Coulombs on an object that has 356 more protons than electrons? 15. An object has an electrical charge of -1.2 x C. How many excess elementary charges does it have? What kind are they? 16. An object has 8.25 x protons and 5.0 x electrons. What is the charge on the object? (First figure out how many excess charges it has. ) 17. Two charged conducting objects are brought together and then separated. How much charge is left on each of the objects? A. +5 μc - 2 μc B. 8 μc - 1 μc C. +10 μc +4 μc