Ch20_SolomonE

toc Chapter 20

=Summary: Current Electricity= Method 2B

1. What (specifically) did you read that you understand well? Describe at least 2 items fully.

I understand the components and conducive nature of a light bulb. I understand how the charge flows through the base and into the filaments and out the threaded metal siding. The charge can also enter through the siding and reverse the direction of the flow. Also, I understand the nature of a circuit. I understand the circular path of the charge and how the charge must be propelled through it continuously in order for sufficient energy to be supplied to, for instance, light a light bulb. Without the loop, the circuit will be left incomplete.

2. What (specifically) did you read that made you feel little confused/unclear/shaky, but further reading helped to clarify? Describe the misconception(s) you were having as well as your new understanding.

When I began this reading, I had thought that the battery provided a different purpose. I thought that the battery was the //source// of the charge. However, it is merely the propelling force which allows the charge to flow off of its original place and through a circuit.

3. What (specifically) did you read that you don’t understand? Please word these in the form of questions.

One aspect of this reading which perplexed me was the drift speeds. How do they work generally? I can sort of understand how the random motion of electrons is generally influenced in one direction, but it's downhill from there.

4. What (specifically) did you read that you thought was pretty interesting, that you didn't know before, or can easily apply to your every day life?

The comparison of a circuit to a water slide was especially helpful. I completely understood the purpose of the battery after it was compared to the water pump. Similarly, I was able to easier understand the energy transfers throughout the circuit in relation to the water slide. For example, the high potential energy at the top (charge ready to be pumped by battery).

=Circuits to the Max (Lab-ish Thing)=

1. Hypothesis: The components of a circuit are wires and a power source. There can also be any other conductors present. Data: Shown on picture below Conclusion: Using the tested materials in various different setups, the essentials were confirmed to be a power source and conductors.

2. Hypothesis: Due to the lack of connection throughout the circuit, the bulbs will go out when the circuit is disconnected at any of the given points. Data: Shown on picture below Conclusion: The hypothesis was confirmed that the bulbs require continuous connection to the circuit to be lit.

3. Hypothesis: The circuit can't be completed without being only connected to conductors. Data: Shown on picture below. This experiment was tried with a variety of different metallic (suspected conductors) and nonmetallic (suspected insulators) substances. Only the metallic ones were able to complete the circuit. Conclusion: The hypothesis was confirmed. The bulbs are lit only when the "something" is a conductor.

Setup #2

Setup #3 5. Hypothesis: The metallic portions of the socket and bulb are conductors. The circuit will therefore be completed if the wires touch the metallic parts of these objects. The circuit will not be complete when the wires touch the nonmetallic parts of the objects. The bulbs are a visual representation of the completed/incomplete circuit. Lit=complete and not lit=not complete. Data: Shown below Conclusion: Confirms hypothesis. This will also insinuate that generally metals are conductors and nonmetals are insulators.

7. Hypothesis: The bulb will only light if the circuit flows from the tip through the threaded portion when using the materiasl given. Data: Shown on picture below. Conclusion: It is possible to create this simplest of circuits using only a wire, a battery and a bulb.

Setup #5

Setup #7















Setup #10

Practice Set 12: 5. a. The compass will deflect in one certain direction depending on which end of the battery the wire which is placed on the compass is closest. It will reverse deflection if battery end is reversed b. There was no decrease/increase in light strength whether the tip or threaded portion of the bulb was touched by any certain end of a wire. c. The matter flowing through the circuit is charged, and therefore affected by the charged end of the battery (attracted to one end and repelled by the other).



Setup #13





Setup #19



Setup #20

21. Capacitors and Charge Flow Figure 1



Bulbs A and B light temporarily when the circuit in Figure 1 below is connected.

1. Will bulbs A and B light when connected as shown in figure 2? Explain your answer in detail.

Yes, they will light. The electrons are being pushed around the circuit by the battery, just like in figure 1. This occurs until the capacitor’s capacity for positive charge is filled. Until then, bulbs A and B will light.

Using a battery, bulbs, wires, and a capacitor explain how:

2. to charge a capacitor Start by setting up a circuit containing the aforementioned components. Connect the wires to either end of the battery. Then connect the wires to the conducting portions of the bulbs so that the positive charge can flow around the circuit. This should look ideally similarly to Figure 1. As the positive charge flows around the circuit, the outside conduction plate of the capacitor will gain positive charge. The inside conduction plate will lose its positive charge, submitting it to the negative end of the battery. Once the capacity to hold positive charge is reached, the capacitor is charged and positive charge will no longer flow because it cannot pass through the insulation plate of the capacitor.

3. to discharge a capacitor

Disconnect the wires from the battery in the setup described above. Touch the ends of the wires formerly on either end of the battery to one another. This will cause the positive charge to return to its former position. In turn, the capacitor loses its positive charge, and it is ready to be charged again.

4. to find out if a capacitor is already charged without discharging it.

Place a compass along the wire of the circuit containing both the battery and the capacitor. Normally, the circuit’s flow of positive charge will cause the compass to deflect in one direction or another. If the capacitor is charged and there is no flow of positive charge, there will be no deflection.



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24.


 * // Answer the following questions based on the air capacitor activity. Explain your reasoning in detail. //**

1. Does any of the air blown into one side of the capacitor come out the other? Explain.

No. The presence of the balloon, or insulator, prevents the flow of air from one side to the other. Air will only occupy one side more than is possible to sustain the current amount in the other side, thus causing some to vacate.

2. How can you recognize a neutralized air capacitor? Explain.

If the balloon in the center does not move when air is inputted into one side, the air capacitor is neutralized. This is usually resulting from some form of blockage on the other end of the capacitor, such as the placement of a finger over the outlet valve.

3. For the air capacitor model, explain what happens when air is forced into one side of the capacitor.

In this circumstance, air is forced into one end of the capacitor. This causes the balloon to swell. There is thusly less space available for air to preside in the opposite end (because of the increase in the end with air being forced in. Some of the air on the other side, with less room, must exit through the valve on the end of said side. 4. In the air capacitor model, explain what happens when air was drawn out of one side of the capacitor.

This situation will effectively produce the opposite effect of the situation described above. Instead of the air vacating the opposite side, the balloon has taken up space where air is being sucked out, and the air may thusly enter the side where the balloon has moved away. There will be an increase in total air on the other side


 * 1) What are the similarities between the purposes of the membrane and the air capacitor and the insulating layer in the electric capacitor?

Like the insulating layer, the balloon (air capacitor membrane) allows for the air to enter on one side because of its elastic quality. This happens, similarly to the insulating layer, only to a certain extent. After this, the balloon will have filled up all of the space on the other side. This will not allow for any more air to enter on the side where air will have entered (similar to positive charge and the conducting layer). Nor will it allow air to exit on the side where air will have exited.

6. What are the physical differences between the insulator in the circuit capacitor and the membrane in the air capacitor?

Physically, there are a few important differences between the air capacitor’s and the circuit capacitor’s insulators. The air capacitor’s layer pushes air physically out of the one end by filling the other end. In a circuit capacitor, the insulating layer is merely a barrier, and there is no contact between the two conducting layers. All of the work to move the charge is done by a power source. Also, the air capacitor’s insulating layer reacts to the movement (input/output) of the circulating matter (air). The circuit capacitor’s insulating layer does not react to the presence of charge flowing into it.


 * Note- some pictures were taken from other physicists in the class

=Circuits Part Deus:=

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 * What effect does the type of bulb have on a capacitor during charging and discharging? **

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 * What are the differences between the filaments of round and long bulbs? (Use a microscope.) **

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3. The longer the filament, the harder it is for the charge to flow. Conversely, the shorter the filament, the easier the flow. Also, the thicker the filament, the easier the flow. The thinner the filament, the harder the flow. Easier flow produces brighter light from a bulb
 * How is air moving through straws analogous to charge moving through a filament? **

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4. Flow rate is simply the amount of charge passing through a given point. It does not take into account velocity, as a lack in velocity can be combated by a thicker area in which the charge can flow. Flow speed does take velocity into account. It is a measure of the charge's distance moved in a certain time.
 * What is the difference between flow rate and flow speed? **

5

 * How does the number of bulbs in a single loop affect the overall current and resistance in a circuit? **

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 * 1) ** Problem Set: [|Resistance] **





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 * Read and Summarize: @http://www.physicsclassroom.com/Class/circuits/ **

ROOM FOR 7

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 * 1) ** Reading and Questions: [|Pressure Difference] **

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 * 1) ** Notes/Activity: [|Color Coding] **
 * 2) ** Practice Set: [|Color Coding] **





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 * How does the number of bulbs side-by-side affect the overall current and resistance in a circuit? **
 * Does adding wires in series or in parallel effect the overall resistance of the circuit? **



13

 * What effect do dueling battery packs have on bulb lighting and flow rate? **
 * How does mixing bulbs in series affect flow rate and pressure in each part of the circuit? **

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 * 1) ** Practice Set: [|Battery Structure] **

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 * 1) Reading: [|Mixing Bulbs]



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 * What is the effect of adding another round bulb in parallel? Set up the 3-bulb circuit in figure on the left, with a gap for a 4th bulb to be added. Then add the 4th bulb to form the circuit in figure on the right. To switch back and forth between the two circuits, you can add the 4th bulb and its socket, and simply unscrew the 4th bulb to break the connection.**



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 * How does the addition of another branch affect flow rate and pressure in the wires? Assemble a circuit with a 3-cell battery and a round and long bulb in series. Using a compass, measure the flow rate in wires A and B. Add a branch with a second long bulb parallel to the long bulb, but don't make the connection. Predict what will happen to the bulb brightness and flow rate when the connection is made. Repeat for a round bulb and for a connecting wire. **



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 * What is the effect of decreasing the resistance of right side of the circuit on: a) the flow rate through the battery; b) the pressure difference across the battery; c) brightness of the left bulb **

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 * 1) ** Practice Set: What determines [|Pressure in the Wires]? **

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 * 1) ** Activity: Ammeter Voltmeter. Work with your classmates to investigate the circuits diagrammed in this [|LabSheet]. Organize the data in some systematic manner that is easy to follow. Analysis: Show the mathematical relationships for current and potential difference for each circuit. Complete the Discussion Questions on this page: [|Discussion Questions]. This will be submitted as a separate lab grade. **







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 * 1) ** T/F: [|25 Statements] **



=Circuits Part Tres: Now With Numbers=


 * Lesson 2 Summary: Electric Current on Electric Circuits**

What is electric current? Flow of electric charge through a medium. Usually is moving electrons in a conductor. Created when charge moves from high potential to low potential.

What is required of an electric circuit? Circuit must be closed conducting loop. Charge must travel in a loop. No gaps. Loop must extend from positive terminal of a power source to negative terminal. Circuit is entirely made of conducting materials capable of carrying charge.

How is electric current measured? Current is the rate at which charge flows past a point on a circuit. Denoted by I. Current is equal to the quantity charge through a point per amount of time.

Current is in amperes (A). 1 ampere (A) = 1 coulomb / 1 second



In electrical terms, what is power? Rate at which electrical energy is supplied to a circuit or consumed by a load. Electrical energy above is supplied to the load by an energy source (ex. electrochemical cell). Cell does work upon a charge. Moves it from negative to positive side. Work done on the charge is equivalent to electrical potential energy change on the charge. Electrical power is the rate work is done.

Power is measured in watts (W). 1 watt = 1 joule / 1 second



What are common misconceptions? Batteries aren't rechargeable. Batteries die when they lose significant potential difference between their terminals.


 * Lesson 3 Summary: Electric Current on Electric Circuits**

What is the path of a typical electron? Long zigzagging path involving collisions and alterations. Electrical potential from battery encourages flow. Collision with wire discourages flow. Electric potential of a charge is lost as it moves through a circuit. Electric potential losses are characterized by voltage drop in external circuit. Accompanying drops are voltage boosts in internal circuit.

What is resistance? Resistance is hindrance to flow of charge. Longer, thinner, and wires of higher resistivity result in higher charge. R= resistance p= resistivity L= length A= area of wire's cross section

What is Ohm's Law? Ohm's Law is a predictor of either V, I, or R, depending on data given. V= voltage I= current R= resistance Can also be written as R=V/I

V and I/R are related directly. I and R are related indirectly.

What is power? P= power V= voltage I= current R= resistance


 * Lesson 4 Summary: Electric Current on Electric Circuits**

What are circuit symbols/diagrams? Circuits can be described easily with symbols/drawings.

Series Diagram

Parallel Diagram

Branching location in parallel is a node.

What are types of circuit connections? Circuits can be in series or parallel or both. In series charge passes through all resistors. In parallel charge splits at branching point. Each device must work in series for circuit to conduct. Adding more resistors equals more overall resistance. Parallel requires indicator bulb (outside of branching paths) to check effect of additional resistors. Parallel does not require all devices to be working. Adding more resistors equals less overall resistance.

What are series circuits? Conducting devices connected so that one conducting path exists. Current slows with more resistors. __Series equations__ Equivalent resistance is addition of resistors Current is same throughout Voltage is not evenly distributed. Total equal sum of parts What are parallel circuits? Conducting devices have separate branches. Multiple conducting paths. __Parallel equations__ Equivalent resistance is inverse of addition of resistor inverses Current is not evenly distributed. Total is sum of parts. Voltage is same throughout.

What are combination circuits?

Combines parallel and series bulb structure. Equivalent resistance must be derived step-by-step. Find equivalent resistance of portions and work through problem from outermost resistance in.