Chapter+20+-+Parts+1+&+2

flat __**Chapter 20 - Parts 1 & 2**__ = = = __**Part 1: Basic Electric Circuits**__ =

1. Investigation: What is needed to make a bulb light?

 * Hypothesis -** Based on what I have previously learned, to make a bulb light there must be a power source attached to the bulb by something, in this case a simple wire.


 * Procedure -** Created various setups using batteries, wires, and a bulb in order to test what is needed to make a bulb light. The description and picture of each scenario is shown below.


 * Data Table:**


 * Description || Picture || Result ||
 * 1 Lightbulb, 2 wires attached, and 1 battery || [[image:#1_dfjhdfdf.png width="375" height="282"]] || On (dim) ||
 * 1 Lightbulb, 2 wires attached, and 2 batteries || [[image:#2_sdfkhjdfdff.png width="401" height="301"]] || On (medium) ||
 * 1 Lightbulb, 2 wires attached, and 3 batteries || [[image:#3_skdjdsfdf.png width="380" height="287"]] || On (well lit) ||
 * 1 Lightbulb, 2 wires attached to negative side, and 1 battery || [[image:#4knjdkfdf.png width="385" height="292"]] || Off ||
 * 1 Lightbulb, 2 wires attached to positive side, and 1 battery || [[image:#_5kjdgfdfdfdf.png width="378" height="284"]] || Off ||


 * Conclusion -** My hypothesis was somewhat correct. I was right that there needs to be a power source (at least one battery) connected to the bulb, but I did not realize that there needs to be a loop. The circuit must be in a circular shape, so that charge is always flowing inside the circuit.

2. Investigation: What will happen to Bulbs 1 and 2 when you disconnect the wires of the configuration below at the various labeled points?



 * Hypothesis -** For all these points, the bulbs will not light. From what I learned in Investigation #1, there needs to be a continuous loop.


 * Procedure** - I set up what is shown in my picture up top and then individually disconnected the wire for each point to see if the bulbs were still lit after I had done so.


 * Data Table:**
 * Point || Result ||
 * A || Off ||
 * B || Off ||
 * C || Off ||
 * D || Off ||
 * E || Off ||
 * F || Off ||


 * Conclusion -** My hypothesis was correct. It did not work for any of the points. There needs to be a continuous loop, so the charge keeps flowing through the circuit to keep the bulb lit.

**3. Investigation: What type of object, when inserted into the space labeled "something" in the loop shown below, will allow the bulbs to light?**

 * Hypothesis -** From my previous knowledge, I think that when metallic objects are placed in that spot, the bulbs will light. When something that is not metallic is placed there, the bulbs will not light.


 * Procedure** - I set up the diagram that is shown above and connected to the wires to various objects where "something" is labelled. I then checked to see if the bulbs were lit.


 * Data Table:**
 * Object || Picture || Result ||
 * Ring || [[image:#1_dskfhdfjdf.png width="327" height="247"]] || Lit ||
 * Ruler || [[image:#2_skdhjdfdfff.png width="331" height="249"]] || Off ||
 * Finger || [[image:#3_sdfjhdfdfff.png width="339" height="256"]] || Off ||
 * Aluminum || [[image:#4_dsfjhkdff.png width="344" height="260"]] || Lit ||
 * Paperclip || [[image:#5_sdkjhsdddd.png width="357" height="270"]] || Lit ||


 * Conclusion -** My hypothesis was correct in that metallic objects that were placed in that spot kept the bulbs light. This is because they allow charge to flow through them. Other objects that do not let the bulbs light do not allow charge to pass through them so easily. This in turn cuts off the charge in the loop and doesn't allow the current to continue.

4. Define and Explain: What is a conductor and what is an insulator? How do you know? How can you test this using our loop configuration?
A conductor is something that allows electric charge to move freely through itself. This means it conducts electricity. In Investigation #3, all the objects that lit the bulbs were conductors because they allowed the charge to move easily in the loop and get to the bulbs. An insulator is something that does not allow electric charge to move freely through itself. This means it does not conduct electricity. In actuality, insulators do not completely stop all electric movement. It just makes it nearly impossible for charge to move through the entire object. In Investigation #3, all the objects that did not light the bulbs were insulators because it did not allow the charge to reach the bulbs. Putting an insulator here is the equivalent to cutting the loop because nothing can go through it. Investigation #3 is a great way to test it!

5. Investigation: What parts of a socket and bulb are conductors and which are insulators? What is the conducting path through the bulb?

 * Hypothesis -** I believe that the tip, threaded section, and filament are conductors, while the glass and black ring are insulators. The first three materials are metallic, while the others are not.


 * Procedure -** I used a set-up that is shown in the pictures below. I connected a wire to various parts of the light bulb to see if it would still light up.


 * Data Table:**
 * Part || Picture || Result || Conductor/Insulator ||
 * Glass || [[image:a#1_dsfjhdsff.png width="335" height="253"]] || No || Insulator ||
 * Threaded Section || [[image:a#2_dfkjhdfdf.png width="336" height="254"]] || Yes || Conductor ||
 * Tip || [[image:a#3_dfkjdfkjdf.png width="350" height="264"]] || Yes || Conductor ||
 * Black Ring || [[image:a#4_dfkdjfffd.png width="365" height="276"]] || No || Insulator ||
 * Filament || [[image:a#5_dfdfdfgfgg.png width="376" height="284"]] || Yes || Conductor ||


 * Conclusion -** My hypothesis was correct. The tip, threaded section, and filament are conductors, while the glass and black ring are insulators. I know that those three things have to be conductors because the tip is what originally brings the charge into the bulb, the threaded section is metallic, and the filament carries the charge, lighting the bulb. The glass and black ring are not metallic and do not seem like conductors

7. Investigation: How can you light a bulb using one battery, one bulb, and one wire only? How many different ways can you do this? What didn't work and why?

 * Hypothesis -** I believe that the tip and metal section needs to be touching either the wire or battery at all times (not saying that they should both be touching the same thing at once, that's hard to do anyway). I know this will work because they are the conductors of the bulb and obviously you can't touch the filament. If the wire or battery is not touching one of those things, it will not light.


 * Procedure -** I arranged the battery, bulb, and wire in many different ways to see which ones lit the bulb and which ones did not.


 * Data Table:**
 * = Description || Picture || Result ||
 * = Threaded section touching battery, wire touching tip || [[image:7111111.png width="335" height="252"]] || Lit ||
 * = Tip touching battery, wire touching threaded section || [[image:722222222.png width="343" height="259"]] || Lit ||
 * = Wire touching battery and other end touching lightbulb tip || [[image:7333333.png width="356" height="269"]] || Off ||
 * = Wire touching battery, other end touching bulb, tip touching battery || [[image:744444444.png width="359" height="271"]] || Off ||


 * Conclusion -** My hypothesis was correct! The conductors (tip and threaded section) needs to be touching either the wire or battery. This allows the charge to flow into the filament and light the bulb. If the wire or battery is touching an insulator instead of a conductor of the light bulb, it will not light up because the charge cannot flow into the filament.

9. Define: What is a circuit?
A circuit is a closed loop that charges can flow through. A source of electricity, such as a battery, provides the energy to keep the charges flowing. It needs to be a full loop with no gaps or insulators that would cause electrons to stop flowing freely.

10. Investigation: What does a compass tell you about what is happening in the wires of the circuit?

 * Hypothesis -** Since there is a current running through the wire, the needle will deflect in some direction


 * Procedure -** I used the set-up that is shown below and kept my eyes on the compass needle to see if it deflected.

This is a picture of the set up only. Pictures of the deflection of the needle are not shown due to the fact that it was too difficult to see the slight movement of the needle in a picture.
 * Data:**

When I performed this experiment, I noted that the needle did deflect when the wire was placed over it. It moved in the clockwise direction.


 * Conclusion -** My hypothesis was correct; the needle did deflect**!** This is due to the charge that is running through the wire. Each charge creates an electrical field. A compass responds to electrical fields, the strongest being the Earth's electrical field. When a small field passes the compass, it deflects, showing that there was indeed charge flowing in the wire.

11. Investigation: What effect does reversing the battery pack have on the compass deflection? What does this mean about the role of the battery in the circuit?

 * Hypothesis -** I think that when the compass points towards the negative part of the battery, the needle will move counter-clockwise. When the compass points towards the positive side of the battery, the needle will move clockwise.


 * Procedure -** I used the same set-up as shown above in Investigation #10. But for two of the trials, I lined up the compass needle facing the positive end of the battery and the other two I lined up the compass needle facing the negative end of the battery. I then checked to see how the needle deflected.


 * Data Table:**
 * Description || Compass Needle Deflection ||
 * Needle facing away from positive end of battery || Counter Clockwise ||
 * Needle facing away from negative end of battery || Clockwise ||
 * Needle facing towards positive end of battery || Clockwise ||
 * Needle facing towards negative end of battery || Counter Clockwise ||


 * Conclusion -** My hypothesis was proved correct. When the compass pointed towards the negative part of the battery, the needle moved counter-clockwise. When the compass pointed towards the positive side of the battery, the needle moved clockwise. The role of battery in the circuit not only provides it with energy, but also determines which way the electric current flows through the circuit.

13. Investigation: What is a Genecon and how does it work? What does it tell you about the role of the battery in the circuit and why?

 * Hypothesis -** I think that the Genecon will serve as an energy source. It will provide energy to the bulb by cranking it.


 * Procedure -** I used the set-up as shown below and cranked the Genecon to see if the bulb lit up.

When the Genecon was cranked, the bulb lit up. When it was cranked at a higher speed, the bulb was brighter. As a lower speed, the bulb was dimmer.
 * Data:**


 * Conclusion -** A Genecon is a generator that creates energy using a crank. When it is cranked, an electrical current is created and flows through the wires into the bulb. This in turn creates a circuit where the Genecon is the power source instead of the traditional battery. It shows that the battery can be replaced by some other power source.

15. Define and Explain: What is a schematic diagram? What are the symbols for the various circuit elements?
A schematic diagram is a simplified version of a real life picture when talking about circuits. Since some things are too complicated to draw, a schematic diagram takes symbols and creates an easier way to draw and visualize certain scenarios. The symbols are shown below.



18. Define and Explain: What is a capacitor and how is it made?
A capacitor is two layers of conducting material (called plates) separated by a layer of an insulator (called the dielectric layer). It stores both charge and energy. The insulating layer prevents movement of the charges from one plate to the other. A simple way to make a capacitor is by placing a sheet of waxed paper in between two sheets of aluminum foil. However, more advanced capacitors look like the ones below.



More about how a capacitor functions is explained in number 19.

19. Investigation: What is the effect of a capacitor on a closed loop?

 * Set-Up:**
 * Hypothesis -** Circuit A will not light, while B will light temporarily when it is attached.


 * Procedure -** I set up the diagram as shown above and below. I first charged the capacitor and then discharged it, noting if the bulb illuminated each time.


 * Data:**

Circuit A did not light.

Circuit B did light temporarily.


 * Conclusion -** A capacitor in a closed circuit functions as follows. Charge moves from the positive end of the power source and builds up in one end of the capacitor (each end is called a terminal). These positive charges in one terminal repel the positive charges in the other terminal. It causes a positive terminal and a negative terminal. This charge passes through a bulb and lights it for a small amount of time before the capacitor comes into play and stops the flow. The amount of time the bulb is lit and how bright depends upon how much charge the capacitor can store. The higher amount, the longer it takes for the capacitor to build up, so the bulb is lit longer and brighter. When the power source is taken out of the equation and a wire attached to the positive terminal touches a wire attached to the negative terminal, the bulbs light for an amount of time because the charges are running through this loop to get back where they were originally.

20. Investigation: What is origin of mobile charge? From where does the mobile charge originate during the charging and discharging process?

 * Set-Up**:
 * Hypothesis -** In the charging process, it originates from the batteries. In the discharging process, it originates from the capacitor.


 * Procedure -** I set up the circuit as shown above and placed the compass where the points were. I did this for charging and discharging and noticed the results of the compass needle.

Charging
 * Data:**
 * Point || Description || Result ||
 * A || Compass at point A with needle facing towards capacitor || Deflects clockwise ||
 * B || Compass at point B with needle facing towards capacitor || Deflects clockwise ||
 * C || Compass at point C with needle facing away from capacitor || Deflects clockwise ||
 * D || Compass at point D with needle facing away from capacitor || Deflects clockwise ||

Discharging
 * Compass Point || Description || Result ||
 * E || Compass at point E with needle facing towards point F and capacitor || Deflects counterclockwise ||
 * F || Compass at point F with needle facing towards capacitor || Deflects counterclockwise ||
 * G || Compass at point G with needle facing towards Point E and capacitor || Deflects counterclockwise ||


 * Conclusion -** My hypothesis was correct. During the charging process, the mobile charge starts off at the batteries where it is brought through the circuit and into the terminal of the capacitor. During the discharging process, the charge originates from the capacitor. Since the battery is now out of the circuit, there is nothing forcing the charge into the capacitor anymore. The positive charges repel one another and then hurry back into the rest of the circuit and distribute themselves evenly.

23. Investigating the Air Capacitor




24. Practice Set: Capacitance
= = = **__Part 2: Resistance__** =

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

 * Set-Up:**


 * Hypothesis** - I believe that one bulb (either the long or round) will make the capacitor take longer to charge and discharge because one is more resistant than the other.

First, I charged the capacitor by connecting the circuit above (first picture I took) with the round bulbs. The two bulbs lit temporarily. I then discharged them and we had the same result, the bulbs lit temporarily. We charged this circuit again with the round bulbs. I then switched the round bulbs for the long bulbs and discharged the capacitor. Now, the two long bulbs __lit for a noticeably longer period of time__ than the round bulbs had.
 * Data:**

I charged the capacitor again using the round bulbs. I then created the set-up as shown in the second picture I took. When I connected both plugs into the capacitor, the crank of the Genecon turned!


 * Conclusion -** Although I did not know which bulb would do what, my hypothesis was confirmed. The round bulb was lit for a shorter amount of time than the long bulb, showing that the round bulb has much less resistance, allowing charge to travel through the bulb faster. This reveals that the bulbs have an impact on the flow rate.

2. What are the differences between the filaments or round and long bulbs? (Using a microscope)
The round bulb had a noticeably thicker filament than the long bulb. On top of this, the long bulb's filament was much longer than the round bulb's filament. This proves that the long bulb has much more resistance than the round bulb.

3. How is air moving through straws analogous to charge moving through a filament?
In class, we breathed through straws to see how easy/hard it was to do through different types of straws. When we used a thick straw, it was easier to breather through compared to a thinner straw. The same is true for charge. Charge flows easier and faster through a thicker conductor rather than a thin one. When we used a short straw, it was easier to breathe through compared to a longer straw. The same is true for charge once again. Charge flows easier and faster through a shorter conductor rather than a long one. My statements about charge have been proven in numbers one and two of part two.

4. What is the difference between flow rate and flow speed?
Flow rate is the amount of charge that passes through a specific point during a specific amount of time. Flow speed is the amount of distance a charge covers for a specific amount of time.

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

 * Set-up:**
 * Hypothesis** - With more bulbs, the lights will become dimmer, but the compass will not be affected.

In Circuit A, the bulb was very bright and the compass deflected like it normally has. In Circuit B, the bulbs were dimmer and the compass did not deflect as much. This was in comparison to Circuit A. In Circuit C, the bulbs were even dimmer and the compass deflected even less. This was in comparison to Circuit C.
 * Data:**


 * Conclusion** - When more bulbs are added to the circuit, there is an increase in resistance. More resistance leads to a lower flow rate, causing the bulbs to receive less charge at a time. This is what dims the bulbs. The same is true for the compass. There is less charge passing over the compass at the same time, so it is deflected less.

10. Practice Set: Color Coding
a. Same brightness b. Same deflection c. Same brightness d. Same deflection e. The battery is a source of constant pressure difference. It creates high pressure and low pressure on both sides of the circuit in each of the examples above.
 * Questions:**

11. How does the number of bulbs side-by-side affect the overall current and resistance in a circuit?

 * Set-up:**
 * Hypothesis** -When we add bulbs side-by-side, I think the overall current and resistance in the circuit will not change. This is because the electric pressure difference will still be the same on the two sides of every bulb.

After testing the above set-up with the entire class, it was shown that the bulbs' brightness was the same in every circuit and that the compass deflected the same amount every time.
 * Data:**


 * Conclusion** -My hypothesis was correct; the overall current and resistance did not change when we added bulbs side-by-side. I can conclude that the current in the wires did not change because the compass deflected the same amount for each set-up. I can conclude that the resistance did not change because the bulbs had the same brightness for each set-up. This was caused by the way the bulbs were aligned. The "parallel" structure of the circuit creates a high electric pressure difference on the two sides of each bulb, which as a result, doesn't change the resistance or current in the circuit.

12. Does adding wires in series or in parallel effect the overall resistance of the circuit?
**Hypothesis** - When another wire is added in series, I think the resistance will not be effected, but the resistance will change when it is added in parallel.
 * Set-up:**

**Data:** Circuit A acts as a comparison for us to measure Circuits B and C. In Circuit B, the needle deflected the same amount and the brightness of the bulbs did not change. In Circuit C, the needle deflected a bit more. The bulb where the wire was added went out and the other one got brighter.

**Conclusion** - By adding wires in a series, like I did in Circuit B, the resistance of the circuit did not change. This shows that wires have very little resistance and does not affect the flow rate of the charge in a circuit. In Circuit C, the bulb went out because I "short circuited" it. The charge took the route with less resistance. Instead of facing the resistance of the bulb, they instead went through the wire that had no resistance. This increased the flow rate, making the compass deflect more and other bulb to become brighter

13. What effect do dueling battery packs have on bulb lighting and flow rate?

 * Set-up:**
 * Hypothesis** - I believe that in series the battery packs will make the bulbs dimmer, but will make them brighter in parallel.

Circuit A - Bulbs lit nicely. Circuit B - Bulbs became dimmer. Circuit C - Very dim bulbs. Circuit D - No light. When the battery packs were added in a parallel structure, the bulbs did not become bright or dimmer.
 * Data:**


 * Conclusion** - I can conclude that some of my hypothesis was right. I was correct that the battery packs in series will make the bulbs dimmer. They act against each other, causing the net voltage to decrease. For example, in circuit C there were 3 packs on the left and two on the right. This created a net battery effect of only 1 cell (3-2=1). This is what would cause the bulb to become dimmer. Dueling battery packs offer resistance in a series. In the parallel structure, the packs did not make the bulbs brighter, but actually did not have any effect.

15. How does mixing bulbs in series affect flow rate and pressure in each part of the circuit?

 * Set-up:**
 * Hypothesis** -I believe that mixing bulbs in series will cause the flow rate to be reduced to what is acceptable to the most resistant bulb in the circuit, in this case the long bulb. Because the resistances are different in the bulbs, the more resistant one (long) will have a greater pressure difference.

When the capacitor was added, the round bulb lights up and the long bulb goes out. Then after a short amount of time, the long bulb lights back up and the round bulb goes out.
 * Data:**


 * Conclusion** - I can conclude that my hypothesis was correct and that mixing bulbs in a series changes the flow rate and pressure in each part of the circuit. When the capacitor is first added, there is little resistance in this object, so it short circuits the long bulb and all the charge goes through it. This speeds up flow rate because of the small amount of resistance, allowing the round bulb to light. Once the capacitor is charged, charges choose to go through the now less resistance long bulb, which is why it is now lit. The round bulb goes out because the flow rate has decreased. This decrease is caused by the long bulb's resistance. Since it is more resistant, the flow rate lowers to a point where it could go through the long bulb. But this low rate is not high enough to light up the round bulb when charge goes through it. This shows that current must flow at the rate of the most resistant object in the circuit.

17. What is the effect of adding another round bulb in parallel?

 * Set-Up:** 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.
 * Hypothesis** - By adding another round bulb in parallel, the bulbs will not be affected and all of them will still have the same brightness.

The bulbs on the bottom and top of the circuit became bright. The two middle bulbs became very dim.
 * Data:**


 * Conclusion** - I can conclude that my initial hypothesis was incorrect. The top and bottom bulbs are bright because there is a high electrical pressure difference across the bulbs. The middle bulbs are dim because the electrical pressure difference is not nearly as high as it is in the other bulbs. I can also conclude that the middle bulbs are dimmer because of a lower flow rate. The charge from the battery hits resistance when going through the top and bottom bulbs, causing the charge to move at a much slower rate.

I can conclude now that this increases the overall current in the circuit and decreases the resistance.

18. How does the addition of another branch affect flow rate and pressure in the wires?

 * Set-Up:** 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.
 * Hypothesis** - I believe the addition of another branch increases flow rate and pressure in the wires.

Circuit #1 - Round bulb lights (previously was off) and both long bulbs light. Circuit #2 - Both round bulbs lit and long bulb dims a bit. Circuit #3 - Round bulb lights and long bulb goes out.
 * Data:**


 * Conclusion** - My hypothesis was somewhat correct, but didn't go much in detail. As you add branches with lower resistance, it increases the current and decreases the overall resistance of the circuit. The round bulb lit up in circuit #1 due to the extra branch increasing the flow of charge by decreasing resistance. Also, this shows that charge takes the path with the least resistance. In circuit #2, the long bulb dims because it is receiving less current. The round bulb (less resistance) is taking away most of the charge that would go to it. In circuit #3, every charge goes through the extra branch because it offers no resistance at all compared to the long bulb which has a lot of resistance.

===19. 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?===
 * Set-up:**
 * Hypothesis -** This will increase the flow rate, have no effect on the pressure difference, and will decrease the brightness of the bulb.

Circuit A - Bulbs are lit. Compass is deflected. Circuit B - Brightness of left bulb decreases. Compass is deflected more. (Compared to A) Circuit C - Brightness of left bulb decreases. Compass is deflected more. (Compared to B)
 * Data:**


 * Conclusion -** My hypothesis was proved correct. When the resistance is decreased on the left side, the flow rate increases, as shown by the needle deflecting more and more. The pressure difference is not affected, proven by the color scheme of each circuit. There is still the same "color jump" across the battery in all three circuits. The brightness of the bulb on the left side decreased when the resistance decreased on the right side. This is because charge moves to where there is less resistance.

21. Activity: Ammeter Voltmeter

 * Conclusion** - I can conclude that in parallel circuits, the voltage of each resistor is equal to one another. The current of the power source in a parallel circuit is equal to the sum of the current of all the other resistors. In series circuits, the voltage of the power source is equal to the sum of the voltage of all the other resistors. The current of each resistor is equal to one another.

23. Conceptual Test on Wednesday, October 26th
=Summary of Lesson 2 - Current Electricity=

The Physics Classroom did a good job of explaining what a current is. Current basically means that there is charge moving through a system. But it also is a quantity. It is the rate at which charge flows past a point on a circuit. This would mean it's a quantity of charge (Q) for an amount of time (t). So it is Q/t. The unit for current is the ampere represented by an A. One ampere = one coulomb per second. With the background knowledge I already have about power, it was easy to take this new concept and fit power into it. In this unit, power is the rate at which electrical energy is supplied to a circuit or consumed by a load (something that uses the energy of a circuit). It is the rate at which work is done. Power is the work done on a charge per an amount of time and is also the energy consumed by the load per an amount of time.
 * What did you read that you understand well? Describe at least 2 items fully.**

I never really understood what a circuit actually is. I knew it created electricity somehow, but the circuit fundamentals eluded me. The beginning diagrams with the battery pack, compass, and light bulb explained circuits well and answered all my preliminary questions. An electric circuit is present when there is a closed loop with charges continuously flowing through that loop. It would not be a circuit if the charges stopped moving. In this case, the battery provides the charge which then moves in a loop from the battery through the wire and into the bulb and then back. It is obvious the charge is moving due to the lighting of the bulb. It is also important to know that the circuit consists of only materials capable of carrying a charge.
 * What did you read that made you feel little confused, but further reading helped to clarify? Describe the misconception you were having as well as your new understanding.**

I didn't understand the light bulb anatomy section at all. I reread it twice and it didn't make sense how the light bulb works.
 * What did you read that you don’t understand?**

The part about the need for a circuit to have an energy supply tied last chapter's material real nicely into this new section. In the cell, there is a positive end and a negative end. In order for this to work, the charge must be brought from the negative side to the positive side. However, this goes against the electric field in the cell. What should occur is that the charge flows form the positive to negative. Since it is the opposite in this case, work must be done. That is where the battery, or energy source, comes into play. It provides the energy needed to move the charge from a low potential area (negative end) to a high potential area (positive end). After it has completed this task, the charge flows naturally through the external circuit.
 * What did you read that you thought was pretty interesting, that you didn't know before, or can easily apply to your every day life?**