Unit4_bruns

Electrostatics
toc Electric Fields

What is an electric field? What are the characteristics of an electric field?
 * a region of space in which another charged object experiences an electromagnetic force
 * experiencing change (test charge)
 * electric field strength= **electrostatic force/test charge**
 * Quantity type || * vector ||
 * Direction || * always the same direction as the force ||
 * Strength ||  ||
 * Units || * newtons/coulombs ||

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

What are electric field lines?

**What are the 4 characteristics of electric field lines?** 1.lines always point away from positive and towards negative 2. the more lines are shown, the stronger the field is 3. field lines surround all charges or charged objects 4. field lines never intersect each other

Can you describe what charges are present in each of the diagrams shown here?

A conductor is in electrostatic equilibrium when the charge distribution (the way the charge is distributed over the conductor) is. Basically, when you charge a conductor the charge spreads itself out. At equilibrium, the charge and electric field follow these guidelines:
 * C1single, negative point charge
 * C2 :2 positive point charges
 * C4:left:negative flowing right- positive more lines
 * C5: lines intersect not possible
 * same strength ones positive one negative
 * the excess charge lies only at the of the conductor
 * the electric field is within the solid part of the conductor
 * the electric field at the surface of the conductor is to the surface
 * charge accumulates, and the field is strongest, on **pointy** parts of the conductor

Since the electric field strength equals zero inside of a conductor, metal boxes of all shapes and sizes make excellent shields for sensitive equipment. It is no surprise that this phenomenon is called **shielding**

Methods of Charging There are 4 methods to creating a charged object. separation of (+) and (-) charges. || positive or negative || conductor or insulator || temporarily separates charges || side closest to the charging object has the opposite charge ||  || Electrons are rubbed off of one object onto another. || neutral || conductor or insulator || permanent until neutralized || depends on the material and what it is rubbed with ||  || When the rod touches a metal sphere, some of the charge from the rod spreads onto the metal sphere because like charges repel one another. When the rod is removed the charge spreads evenly over the metal sphere and remains there because the insulating stand prevents its flow to the ground. || positive or negative || conductor || permanent until neutralized || same charge as the charging object ||  || Bring a charged object next to object to be charged. Add a grounding wire; Remove the grounding wire; Remove the charging object. || positive or negative || conductor || permanent until neutralized || opposite charge as the charging object ||  ||
 * Method Description || Type of Charging Object || Type of Object being charged || Shift |||| End Charge Results ||
 * Polarization
 * Charging by Friction
 * Charging by Conduction
 * Charging by Induction

Electric Charge Distinguish between positive and negative charges. proton || Anion (atom with 1 or more extra electrons) || 1.6 x 10-19 c || 1 electron -1.6 x 10-19 c ||
 * Symbol is Q || Positive Charge (C) || Negative Charge (C) ||
 * Particle Type || Cation (atom missing 1 or more electron)
 * Size || large || small ||
 * Mass || 1.67 x 10-27 kg || 9.11 x 10-31 kg ||
 * Pressure || Low pressure || High pressure ||
 * Cause || Depletion of e- || Excess e- ||
 * Minimum Charge || 1 proton
 * Location || Nucleus || Orbiting the nucleus ||
 * Variety || infinite || Interchangeable, same ||

q= charge || Lesson 39 All material objects are composed of atoms. The material objects are composed of atoms and molecules of elements and compounds giving different materials different electrical properties.
 * Law of electric charge- Benjamin franklin
 * Same charges repel opposite charges attract
 * Only be transferred
 * || Electric Forces ||
 * Relationship to distance || inverse square of distance ||
 * Relationship to charge size || direct proportion ||
 * Types || repulsive or attractive ||
 * Coulomb’s Law || electrostatic force= Ke (q1) (q2)/d^2 distance between charges
 * Compare to Gravitational Force || Fg= Gm1m2/d^2 ||
 * Units || Newtons ||
 * Coulomb’s Constant || 9 x 10^9 Nm^2/kg^2 ||

An atom contains a nucleus and a region of space outside the nucleus. Electrons can be found in the region outside of the nucleus. They are negatively charged and weakly bound to the atom. The nucleus has positively charged protons and neutral neutrons. They are not removable. If they were to be removed there must be a high-energy nuclear occurrence to disturb the nucleus and dislodge its positively charged protons.
 * Proton
 * In nucleus
 * Tightly Bound
 * Positive Charge
 * Massive
 * neutron
 * In nucleus
 * Tightly Bound
 * No Charge
 * Massive
 * electron
 * Outside nucleus
 * Weakly Bound
 * Negative Charge
 * Not very massive

A positively charged particle possesses more protons than electrons. A negatively charged particle possesses more electrons than protons. An uncharged particle has equal numbers of protons and electrons.

Repulsive forces move away from the nature of mutual interaction. Like charges repel. When it is an attractive force, they go towards each other of the mutual reaction.

Conductors are materials that permit electrons to flow freely from atom to atom and molecule to molecule. If there was an object made of a conducting material, the charge can be transferred across the entire surface of the object.Insulators are materials that slow down the free flow of electrons from atom to atom and molecule to molecule.. The particles of the insulator do not allow the free flow of electrons. Because of this charge is never really distributed across the surface of the insulator. [|methods of charging!] Voltage

say you went to the mall and you bought 5 pairs of jeans at guess for a hundred dollars. you think about it seperately electric potential electric potential energy
 * amount of energy **per charge**
 * total amount of work it took to get from there
 * V= change in PE/q
 * J/c= volt

Lesson 40 __**Coulombs**__ Charge in units is known as **Coulombs**. 9 x 109 is the constant and the equation is electrostatic force= Keqq/d2 __**Inverse square relationship**__ There is an inverse square relationship between the electrostatic force and distance. If the distance is doubled, the decrease is 4. You have to square it. The inverse square relationship is expressed by using Coulombs law equation. __**Field force**__ The field force is an unusual force phenomenon that occurs in the absence of physical contact. The charges can either repel or attract when they are held at some distance apart. The charged object then creates an electric field which is an alteration of the space in the region that surrounds it. To see an example of this, one could use a Van de Graff generator which acquires a charge as electrons are scuffed off of a rotating belt while it moves past sharp elongated prongs inside the sphere. __**Electric field strength**__ An electric charge noted by the symbol Q. This electric charge creates an electric field. Q is the source of electric field and can be names the source charge. The intensity of the source charges electric field can be measured by any other places charge. The test charge is used to measure the electric field strength. To find the electric field strength, E=force/charge. The strength of an electric field created by a source charge is inversely related to square of the distance from the source. This is known as the inverse square law. Electric field lines point in the direction that a positive test charge would accelerate if they were placed on the line.. Electric field lines never cross each other. They are also most dense around objects with the greatest amount of charge. When electric field lines meet the surface of an object, the lines are perpendicular to the surface. Last, they 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 video]
 * __Electric field lines__**

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Lesson 41 __**Electric field**__ An electric field is a vector quantity whose direction is defined as the direction that a positive test charge would be pushed when placed in the field. Therefore, the electric field direction if it was positive would be directed away from the positive source. An electric field direction having a negative source is always directed to the negative source. __**Electric Potential**__ Electric potential is the amount of potential energy per unit of charge. Charge moving through the wires of the circuit will come to changes in electric potential as it traverses the circuit. When work is done on a positive test charge to move it from one location to another, the potential energy increases and electric potential increases. When you have the positive test charge and it returns to the negative terminal at a low energy and low potential, the charge is ready to repeat the cycle again. The equation for potential energy equation is Potential energy= PE/Q. Electric potential difference is the difference in electric potential between the final and initial location when work is done on a charge to change its potential energy. EPD is expressed in unit of Volts. An **internal circuit** is the part of the circuit where energy is being supplied to the charge. An **external circuit** is the part of the circuit where charge is moving outside the cells through the wires on the path of the high potential terminal to the low potential terminal. [|Electric potential and electric potential difference]
 * __Electric Potential difference__**

Lab: Ohm's law
Objective one: what is the relationship between pressure difference and flow rate? Hypothesis: There is going to be a linear relationship between the pressure difference and flow rate. With the light bulb, i think there is going to be more of a curved line. Objective 2: What is the relationship between pressure difference and flow rate? (with light bulb)

[[image:amps.JPG width="800" height="519"]]
__**Discussion Questions:**__ 1. In terms of experimental data, how is resistance defined and what are the units? The units are ohms. **Resistance in this situation means that resistance blocks the flow of electricity** **2. Imagine that you had a third resisor that has a much smaller resistance than the ones used in the lab activity?** a) sketch a graph of pressure distance vs. flow rate that shows your 2 original resistors and the new resistor. Clearly label the lines.

b) explain why you drew it this way. **I drew it this way because our R2 was 4700 which was a high resistance. and R1 was only 1000 which was less steep. I drew R3 closer and more of a straight line to the x-axis because if it had even less than these 2 values, it shows that it would have to be a less steep incline and more flat.**  c) how would flow rate through this resistor change as the pressure difference decreases? **The flow rate or current would increase.** 3. Assume that resistor A has 10 times the resistance of resistor b. what would a graph of resistance vs current look like? What about a graph of resistance vs voltage? **I do not believe that the graph would change all that much. The resistor would have not much effect because the resistor does not change, when other things like voltage and current change. I believe that the only part that would change is how much resistance there is going to be.** 4. While cooking dinner, the schools dining hall oven used a 220 volt line and draws 10 A of current when heated to its max temp. What is the resistance of the oven when it is fully heated? 5. A 9 volt battery is connected to a 6 omega resistor. What will the flow rate be through the resistor? 6. Is this resistor ohmic or non ohmic? **Ohmic** 7. What is the resistance of the object from which this data was collected?
 * 220V/10A=22ohms
 * R= v/I
 * 6=9/I
 * =3/2A
 * 1.5 A
 * R= V/l
 * sample
 * R= 1.5/5
 * R=.3 ohms

Lesson 42 An electric circuit is a circuit that if functioning and the charge is flowing through the light bulb filament. The circuit a closed loop through which charges can continuously move. For example, if we knew that the circuit works, we could use a compass and a light bulb, if the light bulb lit up, the compass needle should deflect. The needle shows the detection of moving charges. When this happens, there is a current- a flow of charge within the circuit.

In order to have a circuit there must be 2 requirements. First, there must be an energy supply (such as a battery) that can do work to make the charge move from a low energy location to a high energy location. This then creates an electric potential difference across the two ends of the external circuit. Second, there HAS to be a closed conducting loop in the external circuit that go from high positive potential, to negative potential.

Current is a rate quantity. It can be found by using I= quantity of charge/time. The units is ampere (A). To light the light bulb, it is the job of the moving electrons in the filament to light the bulb. When those electrons leave the bulb, new/more electrons enter the filament and they become responsible for lighting the bulb. This is analogous to a pipe in a house because the water in the pipes of a home move together.

Power is the rate at which electrical energy is supplied to a circuit or consumed by a load. The electric energy is supplied by the load (lightbulb, beeper, motor). A cell does work on a charge to move it from the low to high energy. The work is equal to the electric potential energy of the charge. This is where we get the power equation. Power= work/time. The unit for electrical power is a watt. [|Electric current video]

Lesson 43
What is the journey of an electron? An electron travels through the circuit bumping into other atoms of the conducting wire. When they collide, there is an alteration in the path making it look sort of zig zag motion, discouraging the flow of charge. Because there is energy loss in the load and the electric potential is decreased while it goes through the external circuit. The electric energy supplied by the electrochemical cells all become used up in the external circuit.

Resistance is the hindrance to the flow of charge. The total length of the wire affects the resistance. When the wire is longer, there is more resistance. There is a direct relationship between the amount of resistance encountered by charge and the length of wire it must traverse. But, there is more likelihood to have a collision in a long wire because resistance occurs as a result of a collision between the charge carriers and the atoms of the wire.

If we had a wider wire, the flow would be at a higher rate than if we had a smaller less wide wire. The wider wire will have less resistance. Therefore, charge will flow at higher rates through wider wires with bigger cross-sectional areas than through the thinner wires.

The material that a wire is made of can effect resistance. Some materials, such as gold are better conductors and give off less resistance to the flow of charge. To know the conductivity ability, it is indicated by the resistivity. The resistivity depends on the material's electronic structure and its temperature.

Ohms law can be stated as follows= Voltage(potential difference)= current(resistance) V=IR. This equation shows the relationship between current, resistance, and potential difference. [|resistivity]

Lesson 44
Symbols for circuit diagrams When you make a series circuit, you can see that the circuit can be constructed by connecting light bulbs where there is a single pathway for the charge flow. The bulbs are on the same line with no branching points. When more and more light bulbs are added, the bulbs brightness starts to decrease. This shows that the current in the circuit is decreasing. When more resistors are added, the overall current within the circuit decreases. The decrease in current is consistent with the conclusion that the overall resistance increases. All the light bulbs go out if something is touched.

The overall current for a parallel connection shows that you need a indicator bulb. The indicator bulb is placed outside of the branches and allows the observer to look at the affect of additional resistors on the overall current. The addition of more resistors causes the indicator bulb to get brighter. As the number of resistors increases, the overall current also increases BUT there is LESS OVERALL RESISTANCE. No lights would go out; it would just change to a 2 bulb circuit if you had 3 bulbs.

For equivalent distance for a series circuit, you just add up all of the numbers. V= IR I=Vbatt/r1 +r2 THE SAME R= add up together P= IV For equivalent distance for a parallel circuit, you must do inverse of the fractions. V= given! same I= V/R R= fractions- do inverse P= IV [|Parallel and series curcuits]

__**Important:**__ Electric charge Electric force Electric field List 4 methods of charging a neutral object
 * Same charges repel opposite charges attract
 * Can only be transferred
 * Whether an object has extra electrons and protons giving it energy
 * A property of matter that allows it to experience an electric force when near other charged particles. An imbalance in number of protons and electricity’s
 * Interaction between 2 or more objects
 * Charged objects can effect neutral objects too
 * Depends upon polarity-polarized creating a charged objects
 * The interaction between 2 charged particles, either repulsive or attractive
 * a region of space in which another charged object experiences an another force. Directly proportional to the size of the source and inversely proportional to the distance 2
 * a region of space where a charge will experience a force from another charge
 * induction
 * conduction
 * friction
 * polarizing

Charge in units is known as **Coulombs**. 9 x 109 is the constant and the equation is electrostatic force= Keqq/d2 There is an inverse square relationship between the electrostatic force and distance. If the distance is doubled, the decrease is 4. You have to square it. The inverse square relationship is expressed by using Coulombs law equation.