Ch18_SolomonE

toc = = = =

= = =Guiding Questions:= Nucleus packed with the majority of the mass including neutrons and protons. Negative orbitals with electrons. Can be either positively, negatively, or neutrally charged.
 * 1) What is the structure and properties of an atom?

2. What is the symbol and unit of electric charge? C ; Coloumb

3. Distinguish between positive and negative charges in as many ways as possible. Positive: lost electrons, attract negatively charged particles, repel positively charged particles, incomplete electron shells Negative: more electrons than protons, attract positively charged particles, repel negatively charged particles, usually completed electron shells to a necessary point

4. Describe the properties of electric forces. Oppositely charged particles attract. Similarly charged particles repel. Neutrally charged particles stand indifferent. Charged particles will attract neutrally charged particles.

5. Distinguish between insulators and conductors. Conductors: Permit the flow of electrons from atom to atom, minimizes the repulsive forces, charge distributes quickly amongst the conductor Insulator: Impede the flow of electrons from atom to atom, charge is rarely distributed amongst the insulator, charges can not escape into the surroundings even if the surrounding objects are conductor

6. What is polarization? The separating of opposite charges within an object

7. How does a neutral object acquire charge? The object will exercise its electron affinity

8. Distinguish between the 3 charging processes.

Friction: Electrons rub off of one object and onto another, creating an imbalance of electrons within both of the objects. Induction: Separate the charges through the presence of a charged object. Then separate the objects, which have had their charges separated through the use of an insulator. Conduction: Through the use of a conductor, electrons will either move to or from one conductor and onto another, thus creating a net charge.

9. What is the law of electric charge? The net charge between two objects that have just gained opposite charges stays the same as it was before they were charged. Charge is neither created nor destroyed, but rather transferred, during the charging process.

10. What is an electric field?

The net charge between two objects that have just gained opposite charges stays the same as it was before they were charged. Charge is neither created nor destroyed; it is transferred.

11. What are the characteristics and properties of an electric field? See applet: [|http://www.gel.ulaval.ca/~mbusque/elec/main_e.html] - The electric field will be zero beneath the surface of any conductor Electric fields are perpendicular to the surface that they correspond to At points where the surface is most curved/pointed, electric fields are the strongest

12. What are the “players” involved in an electric field?

There is a source of field, represented by the symbol Q, gives off the field lines. There are also experiencing charges, which are represented by the symbol q. There is not necessarily only one experiencing charge in an electric field.

13. What are electric field lines? The are visual representations of the force emitting from an electric field.

14. What are 4 characteristics of electric field lines? Electric field lines always extend from positive to negative Electric field lines never cross Electric field lines are denser surrounding objects with greater charge Electric field lines are perpendicular to the surface of an object that they meet.

15. Go to []. Scroll to the bottom of the page and do the “Check Your Understanding” questions.

In C, the lines are directed towards a positively charged object. In D, the lines are not symmetrically positioned In E, the lines are directed away from a negative charge. Electric field lines never cross. Erin's lines crossed. D- Electric field lines are directed towards object A, which therefore must be negative. They are directed away from object B, which therefore must be positive. D,A,E,C,B. Electric field strength is greatest where lines are the closest and weakest where lines are the furthest. Objects A, C, F, G, H, and I are positively charged. Objects B, D and E are negative. Electric field lines always approach negatively charged objects and move away from positively charged objects B < A; C < D; G < E < F; J < H < I

=Summaries:=

The structure of an atom and how it underwent an evolution of sorts through scientists gaining eventual and more thorough knowledge of it as time passed; Neutral vs. charged objects and how neutral objects have equal amounts of electrons and protons and charged objects have excess of one or the other This was all review All review, yet again We did not go over this in class b/c it was all review
 * __1__**
 * 1) What (specifically) did you read that you already understood well from our class discussion? Describe at least 2 items fully.
 * 1) What (specifically) did you read that you were a little confused/unclear/shaky about from class, but the reading helped to clarify? Describe the misconception you were having as well as your new understanding.
 * 1) What (specifically) did you read that you still don’t understand? Please word these in the form of a question.
 * 1) What (specifically) did you read that was not gone over during class today?

The charge interactions and the process with which objects exchange electrons to gain charges. The ideas of an insulator vs. a conductor and how certain objects will gain charges easier. Charging by induction/conduction. The two ideas were simply not explained fully in class. Through the reading I understand that charging by induction is the process through the distribution of a charge uniformly throughout a surface because of the presence of an exterior charge. Also, I understand that charging by conduction is charging through the touching of two conductors in order to spread a charge from one object to another. Coloumb’s Law and Inverse Square Law; please explain b/c I got lazy and didn’t read about them thoroughly. The process of grounding, or the restoring of a charged object back to magnetic neutrality.
 * __2__**
 * 1) What (specifically) did you read that you already understood well from our class discussion? Describe at least 2 items fully.
 * 1) What (specifically) did you read that you were a little confused/unclear/shaky about from class, but the reading helped to clarify? Describe the misconception you were having as well as your new understanding.
 * 1) What (specifically) did you read that you still don’t understand? Please word these in the form of a question.
 * 1) What (specifically) did you read that was not gone over during class today?

Charged interactions as forces and how this differs from gravity b/c it can both attract and repel; Newton’s laws of motion corresponding to the interaction between charged objects and how it works similarly to any other set of forces Why does an object continue accelerating away from an object the farther it gets despite the fact that the force would have less of an effect? Wouldn’t it begin to move away, yet at a lower velocity? Nothing Nothing
 * __3__**
 * 1) What (specifically) did you read that you already understood well from our class discussion? Describe at least 2 items fully.
 * 1) What (specifically) did you read that you still don’t understand? Please word these in the form of a question.
 * 1) What (specifically) did you read that was not gone over during class today?
 * 1) What (specifically) did you read that was not gone over during class today?

Intensity: Electric field strength is a vector quantity. electric field strength is not dependent upon the quantity of charge on test charge. Electric field strength is location dependent, magnitude decreases as distance from a location to the source increases. Field Lines: Principles: At locations where electric field lines meet surface of an object, lines are perpendicular to the surface.
 * __ 4 __**
 * field force ** is used to explain force phenomenon that occurs in the absence of physical contact. charges can either repel or attract when held apart. the space surrounding a charged object creates an electric field - an alteration of the space in the region that surrounds it. Other charges feel the unusual alteration of the space. Van de Graaff generator, a large conducting sphere that acquires a charge as electrons are scuffed off of a rotating belt as it moves past sharp elongated prongs inside the sphere. the strength of the electric field is dependent upon amount of charge that creates the field and the distance from the charge.
 * Q ** is the source of the electric field, the **source charge**. strength could be measured by any other charge placed somewhere in its surroundings. The charge used to measure the electric field strength is a ** test charge **. denoted by symbol ** q **. will experience an electric force - either attractive or repulsive.
 * electric field lines **, direction that a positive test charge would accelerate if placed upon line. lines are directed away from positively charged source charges and toward negatively charged source charges.
 * Electric field lines always extend from a positively charged object to a negatively charged object, from a positively charged object to infinity, or from infinity to a negatively charged object.
 * Electric field lines never cross.
 * Electric field lines are most dense around objects with greatest charge.

=Classwork Pictures:= (Generally taken covering 2/3 of the page from the top, then from the bottom. If work looks like it appears twice, it is in the overlapping picture area.)








 * Balloon Activity:**


 * More Classwork Pictures:**

=Sticky Tape Lab:=
 * #5: Sketch with labeled force vectors for two top tapes

close enough to affect each other.

The repel

|| Sketch with labeled force vectors for two top tapes half as far apart as left sketch

|| No reaction || #9: Describe foil on foil interaction No reaction ||
 * #8: Describe paper on paper interaction
 * #13: Describe top tape and foil interaction

Attract

Diagram with forces || Describe top tape and paper interaction

Attract

Diagram with forces || Repel
 * #13: Describe top tape and top tape interaction

Diagram with forces

|| Describe top tape and bottom tape interaction Attract

Diagram with forces

||
 * #13: Describe bottom tape and foil interaction

Attract

Diagram with forces || Describe bottom tape and paper interaction

Attract

Diagram with forces ||

Attract
 * #13: Describe bottom tape and top tape interaction

Diagram with forces || Describe bottom tape and bottom tape interaction Repel

Diagram with forces || Attract || Describe PVC rod and foil interaction Attract || Attract || Describe PVC rod and bottom tape interaction Repel || Attract || Describe Lucite rod and foil interaction Attract || Repel || Describe Lucite rod and bottom tape interaction Attract || Repel b/c both positive || State top and bottom tape interaction based on charge Attract b/c opposite charges ||
 * #14: Describe PVC rod and paper interaction
 * #14: Describe PVC rod and top tape interaction
 * #15: Describe Lucite rod and paper interaction
 * #15: Describe Lucite rod and top tape interaction
 * #16: State top and top tape interaction based on charge
 * #16: State bottom and bottom tape interaction based on charge

Repel b/c both negative ||  ||


 * Discussion Questions: **

When the materials are rubbed against each other (friction requiring no initial charges), or placed near each other (conduction/induction requiring at least one charged), electrons are transferred from the one with the lesser affinity to the one with the greater electron affinity. The one with more electrons is now negative and the other is positive.
 * 1) Explain how materials become charged through their interaction with one another.

2. Why, when you stroke a cat's fur, or comb your hair on a cold, dry day can you hear a crackling sound? Doing these things in a darkened room, you can actually see sparks. Explain. This is due to the transfer of electrons between materials. A.k.a. static electricity. The protons in one material ultimately will create this crackling by reacting with the electrons of the opposite material.

3. Photocopying machines use the principles of electric charges. Do research to find out how photocopying machines work. Be sure to list your sources. The photocopy machine scans the paper, creating an electrical shadow of the paper by reflecting off of the white (non-ink) and black (ink) surfaces. The electrical shadow is rotated around a belt and coated with a layer of ink when it reaches the ink plenum because the toner has received a strong electrical charge. The paper, as it passes another conveyor belt, is also given a strong electrical charge. The charge of the paper then draws the charge of the ink, which causes them to stick to one another. Viola, photocopied!

http://www.explainthatstuff.com/photocopier.html PVC(++), Wool (+++++), Styrene (++++), Teflon (+), Polyester (+++)
 * 1) Materials have a characteristic which evaluates their attraction for electrons. The Triboelectric Series orders materials by their affinity for gathering electrons through contact from other materials. The materials toward the top of the list are likely to give up electrons in these interactions whereas those at the bottom are more likely to gain electrons. Five materials are ranked as follows, with more positives meaning least desiring electrons.


 * 1) Rank the materials on the scale below:

Teflon PVC Polyester Syrene Wool

4. Determine the net charge on each item when the following pairs of materials are rubbed together. (In other words, which ends up giving up electrons and which ends up accepting them?) PVC
 * 1) PVC and Wool

Teflon
 * 1) PVC and Teflon

PVC
 * 1) PVC and Polyester

Teflon
 * 1) Teflon and Polyester

Syrene
 * 1) Styrene and Wool

Revisit your hypotheses and answer the objectives in light of your observations. Be sure to be specific, supporting your statements with evidence from the lab.
 * Conclusion: **

Different materials will generally gain one charge or the other in the presence of a charged object. This depends on the object’s electron affinity and whether it is a conductor or an insulator. This will cause the material to be either attracted or repelled by the charged object.
 * 1) How do different materials react in the presence of a charged object?

2. How do you distinguish between positively and negatively charged objects? This can be achieved solely empirically. There is no other logical way to distinguish which object is charged with which orientation unless an object of a known charge is introduced and allowed to interact.

3. How do you determine the exact net charge on an object? This must be done scientifically. This requires knowledge of the electrical force field acting upon an object and the object’s charge which is being acted upon. = =


 * Concept Map:**