Ch20_LitmanovP

toc =**Part 1: Circuits**=

=**Investigation 1**= What is needed to make a bulb light?

Hypothesis: A closed electrical circuit is needed to make a bulb light. The circuit will include battery(ies), light bulb(s), and electrical wires. A larger power source (ie. more batteries) will cause the light bulbs to be brighter.

Data:



Conclusion:

Based on my observations and data table, my hypothesis was correct. A closed circuit is necessary to make the bulb light and a larger power source (more batteries) results in a brighter bulb.

=**Investigation 2**= What happens to Bulbs 1 and 2 when you disconnect the wires of the configuration below at the various labeled points?

Hypothesis:

At any point where the circuit is not continuous, electrical current will not flow and the bulbs will not light.

Data:



Conclusion:

My initial hypothesis was correct. All the tested situations had points where the circuit was incomplete, and so electrical current did not flow and the bulbs did not light.

=**Investigation 3**= What kind of object, when inserted into the spot labeled "something," in the loop shown below, will allow the bulbs to light?

Hypothesis:

An object that is a conductor will allow the bulbs to light and an object that is an insulator will not allow the bulbs to light. My rationale for this hypothesis comes from the definitions of conductor and insulator. A conductor is an object/material that allows electrons to freely flow through it and an insulator does not. The free flow of electrons is crucial for electrical current to flow through a circuit and light a bulb.

Data:


 * Object || Data || Result ||
 * Foil || [[image:Photo_on_2011-10-12_at_22.41_#2.jpg width="405" height="305"]] || On ||
 * Paper || [[image:Photo_on_2011-10-12_at_22.45.jpg width="375" height="287"]] || Off ||
 * Metal Pin || [[image:Photo_on_2011-10-12_at_22.51_#2.jpg width="366" height="277"]] || On ||
 * Leather || [[image:Photo_on_2011-10-12_at_22.53.jpg width="400" height="301"]] || Off ||

Conclusion:

My hypothesis was correct. Both objects made of metal (metal pin and foil) consist of metallic bonds which allow the free flow of electrons - these are conductors. The other objects (paper and leather) don't allow the free flow of electrons and are insulators.

=** 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 any object or material that is metallic or made of metal. This is because metals are formed from metallic bonds of their atoms and allow the free flow of electrons throughout the metal. That is why any metallic object, or conductor, can be used to complete a circuit. An insulator is the opposite of a conductor. It hinders the flow of electrons; it is anything made from non-metal. An insulator cannot be used to complete a circuit. We can test this using our loop configuration by attaching the wire to different objects/materials and seeing which objects/materials complete the circuit and cause the bulbs to light. Those that do cause the bulbs to light are conductors and those that don't are insulators

=**Investigation 4**= What parts of a socket and bulb are conductors and which are insulators? What is the conducting path through the bulb?



Hypothesis: The conductors on the socket are the clips and the plates. The conductors on the bulb are the tip and threaded section and the filament. The insulator on the socket is the base. The insulator on the bulb is the black ring and the glass. The conducting path through the bulb is either entering through the threaded section, passing through the filament, and exiting out the tip, or entering through the tip, passing through the filament, and exiting out the threaded section. All the materials made of metal will be conductors and all non metal materials will be insulators.

Data:


 * Part || Data || Result ||
 * Tip || [[image:Photo_on_2011-10-13_at_00.05_#2.jpg width="371" height="280"]] || Conductor ||
 * Threaded Section || [[image:Photo_on_2011-10-13_at_00.02.jpg width="364" height="275"]] || Conductor ||
 * Black Ring || [[image:Photo_on_2011-10-13_at_00.08_#2.jpg width="359" height="271"]] || Insulator ||
 * Glass || [[image:Photo_on_2011-10-13_at_00.05_#3.jpg width="355" height="269"]] ||  ||
 * Clip || [[image:Photo_on_2011-10-12_at_23.59_#2.jpg width="356" height="269"]] || Conductor ||
 * Base || [[image:Photo_on_2011-10-12_at_23.59.jpg width="352" height="265"]] || Insulator ||
 * Plate || [[image:Photo_on_2011-10-13_at_00.00.jpg width="352" height="268"]] || Conductor ||

Conclusion:

My hypothesis was correct. All parts of each objects that were made of metal were conductors and all non metal parts were insulators. Metal allows the free flow of electrons making them conductors and anything non-metal hinders the flow of electrons making it an insulator. Current can flow through the threaded section of a bulb out the tip or vice versa. Either way will light the bulb.

=**Practice Set: The CCP**=





=**Investigation 5**= How can you light a bulb using one battery, one bulb, and one wire ONLY? How many different correct ways can you do this? What didn't work and why?

Hypothesis:

You can only light a bulb using one battery, one bulb, and one wire if the a closed circuit exists between the battery, bulb, and wire. There are 4 different ways to do this: tip or threaded section on the positive with the wire connecting the bulb to the negative, and tip or threaded section on the negative with the wire connecting the bulb to the positive. Configurations that do not make a closed circuit will not work.

Data:

bulb connected to positive. Other end of wire touching threaded section of bulb. || || Light || threaded section of bulb touching positive end. Other end of wire touching tip of bulb. || || Light || ends of battery. The threaded section is at the positive end but not touching the wire. || || No Light || ends of battery. The tip of the bulb is at the positive end but not touching the wire. || || No Light ||
 * Setup || Data || Result ||
 * Wire connected to negative end of battery and tip
 * Wire connected to negative end of batter and
 * Same as first, but negative and positive switched. || [[image:apphysicslevine/works_2.png width="223" height="160" caption="works_2.png"]] || Light ||
 * Same as second, but negative and positive switched. || [[image:apphysicslevine/works_1.png width="188" height="165" caption="works_1.png"]] || Light ||
 * Wire connected to positive and negative
 * Wire connected to positive and negative

Conclusion: My hypothesis was correct. When the circuit was not complete, as in the last two, the bulb did not light. There were only 4 ways to do this, and all 4 involved a closed circuit.

=**Practice Set: Basic Circuits**=







=**Define: What is a Circuit**=

A circuit is a closed loop with a power cell (ie. battery) and conducting material connected to it allowing electricity to flow freely. The loop must be closed (everything must be connected) in order for it to be a circuit and for current to flow. If any conducting material is touching an insulator, the circuit will be disrupted and current will not flow.

=**Investigation 6**= What does a compass tell you about what is happening in the wires of the circuit?

Hypothesis:

A compass tells you that a circuit is complete and current is running through the wire. If the circuit is complete and current is flowing, the needle in the compass will deflect. The compass needle will deflect in order to be perpendicular to the to the current.

Data:

media type="file" key="Movie on 2011-10-13 at 14.35.mov" width="300" height="300"

Conclusion:

My hypothesis was correct. When circuit was closed and the wire was placed directly over the needle of the compass, the needle deflected slightly, showing that current was indeed flowing. The needle moved in the clockwise direction.

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?
 * Investigation 7**

Hypothesis:

Reversing the battery pack causes the compass to deflect in the opposite direction. This means that the batter pumps electrons in only one direction.

Data:

media type="file" key="Movie on 2011-10-13 at 21.33.mov" width="300" height="300"

Conclusion:

My hypothesis was correct. The compass deflected in the opposite direction when the battery was reversed. Because of this, it can be concluded that the battery is responsible for pumping the electrons only one way - the electrons went the opposite direction when the battery was reversed which caused the compass to follow suit.

=**Practice Set: Wires**=







=**Investigation 8**= 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:

A Genecon is a handheld device that serves the same function as a battery. It has gears and a motor and a hand crank connected to the gears.

Data:

media type="file" key="Movie on 2011-10-14 at 14.15.mov" width="300" height="300"

Conclusion:

My hypothesis was correct. The Genecon serves the same purpose as the battery. When the gears are cranked, the work provided by my muscles is used to create energy to turn the gears inside the Genecon which move to provide energy for the motor. The motor then utilizes this energy to pump charge (which is present everywhere within the circuit) throughout the circuit to make the bulbs light. The harder the crank is turned (more work, which means more energy), the brighter the bulbs will be.

=**DEFINE AND EXPLAIN**= What is a schematic diagram? What are the symbols for the various circuit elements?

A schematic diagram is a diagram used to sketch a circuit without using actual pictures - symbols are used instead. It allows for the use of universal symbols to depict any circuit. This is beneficial as there are many different types of batteries, wires, bulbs, etc. and it can get very confusing.

These are the symbols:



=**Practice Set: Schematics**=







=**Reading: Capacitance**=





=**DEFINE AND EXPLAIN**= What is a capacitor and how is it made?

A capacitor is a device made of three layers - two conducting plates separated by an insulating layer - encased in a cylindrical casing, with two screws coming out the top connected to both plates. One connects the capacitor to the circuit via these screws. A capacitor is used to store electrical charge. When the capacitor is connected to a circuit, the batteries pump positive charge from the positive end of the battery and onto the top plate of the capacitor. Because of the insulating layer within the capacitor, charge does not move freely through the capacitor. Instead, positive charge builds up on the top plate and this excess charge causes the positive charge on the bottom plate to flow due to repulsion. This creates current and lights the bulbs for a brief moment until the batteries cannot pump any more positive charge onto the top plate. At this point the capacitor is charged, and that stored charge can be released through discharging to once again provide current in the circuit and light the bulbs.

=**Investigation 9**= What is the effect of a capacitor on a closed loop?



Hypothesis:

The bulbs in Circuit A will not light unless the capacitor was charged prior to connecting it to the circuit. Upon connecting the capacitor to Circuit B, the bulbs will briefly light. If the capacitor is discharged, the bulbs will also light.

Data:

media type="file" key="Movie on 2011-10-16 at 20.44

Conclusion:

My hypothesis was correct. A capacitor is made up of two conducting plates separated by some insulating material. The positive charge flows through the circuit and builds up on one plate of the capacitor and in effect pushes, via repelling, the positive charge on the other plate out the other side. The bulbs light up briefly when the capacitor is connected to the circuit. The amount of time they light up for signifies the amount of time it took for a plate on the capacitor to reach the same electric potential as the batteries. The bulbs go out after this time because the batteries can no longer pump positive charge onto this plate because there is no more "room," as the electric potential is equal. At this point all the positive charge has been repelled off the other plate and the circuit is now incomplete because charge can no longer flow. If one wire is disconnected from one end of the battery and touched to other end, the electric potential is no longer equal - the potential is higher in the capacitor - so for the same amount of time as before, the bulbs will light, as the built up positive charge is discharged - it flows back around the circuit causing the bulbs to light up again. The charge ends up on the other terminal of the capacitor replacing the positive charge that was "lost" when it was repelled during the charging phase. This is called discharging and the former is called charging. When charging, energy becomes stored in the capacitor in the form of electric potential. When discharging, this energy is released.

The capacitor is used to store electric charge and release it at a later time to provide current without the need of a batter or other power source.

=**Investigation 10**= What is origin of mobile charge? From where does the mobile charge originate during the charging and discharging process?



Hypothesis:

In the charging process, the mobile charge originates from the positive particles all throughout the conducting material in the circuit; the batteries will provide the energy to pump this charge throughout the circuit and cause it to build up on the top plate of the capacitor. In the discharging process, the mobile charge originates from the capacitor - from the built up charge stored in the top plate of the capacitor as a result of the charging process.

In the charging phase, the compass will in the one direction. In the discharging phase, the compass will deflect in the opposite direction.

Data:

Charging

media type="file" key="Movie on 2011-10-16 at 20.34.mov" width="300" height="300"

Discharging

media type="file" key="Movie on 2011-10-16 at 20.34

Conclusion:

My hypothesis was correct. The origin of mobile charge during charging is the positive charge already present in the conducting material and during discharging the mobile charge originates from the build up of charge on the top plate of the capacitor. In order for this hypothesis to be true, the direction of the current during charging should be opposite from the direction during discharging. The data above supports this. During charging the compass deflected one way and during discharging it deflected the other way. This is because during charging, the charge builds up on the top plate in one direction and during discharging the charge "comes off" the top plate going along the same path but in the opposite direction.

=**Practice Set: Electrical Energy**=






 * 1) 7 (above is incorrect)



=Investigating the Air Capacitor=







=**Practice Set: Capacitance**=



= = =**10/7/11 - Lesson 2 Summary**=

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

I understand well the workings of a circuit. In order for current to flow, the circuit loop must be complete, and that charge moves continually through the circuit, from the positive to the negative and all over again.

I also understand what current is. I understand that current is quantitative and qualitative. Current can be measured in amperes and it is the rate at which charges passes a certain point. It can be calculated by dividing charge (Q) by time (t). Current = I = Q/t.

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.

I didn't understand at first how electric fields played a role, but further reading helped me understand that pumping charge against the electric field puts the charge in an area of high electric potential. From there, they flow naturally from high potential to low.

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

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?

I found it interesting how they compared rides at a water park to electric circuits. It made everything a lot more clear - just like a circuit water moves from high potential to low potential.

=**Part 2: Resistance**=

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

Hypothesis: The type of bulb will have no effect on discharging.

Data:

Charging and Discharging through Round Bulbs media type="file" key="Movie on 2011-10-18 at 14.18.mov" width="300" height="300"

Discharging through Long Bulbs

media type="file" key="Movie on 2011-10-18 at 14.34.mov" width="300" height="300"

Discharging through Genecon

media type="file" key="Movie on 2011-10-18 at 14.36.mov" width="300" height="300"

Observations:

Discharging through Round || Bulbs stayed lit for the same amount of time during charging and discharging. || Discharging through Long || The Long bulbs stayed lit much longer and were brighter than the Round bulbs. || Discharging through Genecon || Crank turned for slightly less time than the Round bulbs stayed lit. ||
 * Bulb/Device || Charging/Discharging || Observations ||
 * Round || Charging through Round and
 * Long || Charging through Round and
 * Genecon || Charging through Round and

Conclusion: My hypothesis was incorrect. The round bulbs, long bulbs, and Genecon have different properties and so they have different resistances. The Genecon has the least resistance and so discharging through it took the least time. The Long bulbs have the most resistance and so they stayed lit the longest and were also the brightest. This is because the long bulbs resisted the most charge going through them and the charge being discharged from the capacitor took more time to dissipate.

2.
What are the differences between the filaments of round and long bulbs? (Use a microscope.)

Hypothesis: The round bulb will have a thicker filament and the long bulb will have a thinner filament.

Data:

Round bulb filament:



Long bulb filament:

completely coiled || half coiled ||
 * Bulb || Filament ||
 * Round || Thicker than long; shorter than long;
 * Long || Thinner than round; longer than round;

My hypothesis was correct, but incomplete. Round bulbs have a much thicker filament and are completely coiled. Long bulbs have a much thinner filament and are only half-coiled. Also, the round bulb's filament is much shorter than the long bulb's. Because the round bulbs have a thicker and shorter filament, there is less resistance. As a result, round bulbs are brighter than long bulbs when lit.

3.
How is air moving through straws analogous to charge moving through a filament?

The wider and shorter the straw the easier it is to blow air through it. The same is true for filament. The thicker and shorter it is, the easier it is for charge to move through it.

4.
What is the difference between flow rate and flow speed?

Flow rate measures how much charge moves past a point in a certain amount of time. Flow speed measures how the distance a charge moves over a certain amount of time.

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



Hypothesis:

The more bulbs the higher overall resistance of the circuit and the slower the flow rate.

Data:

Compass deflection with 1 bulb:

media type="file" key="Movie on 2011-10-18 at 14.41.mov" width="300" height="300"

Compass deflection with 2 bulbs:

media type="file" key="Movie on 2011-10-18 at 14.42.mov" width="300" height="300"

Compass deflection with 4 bulbs:

media type="file" key="Movie on 2011-10-18 at 14.44.mov" width="300" height="300"

Observations:


 * # of Bulbs || Brightness || Compass Deflection ||
 * 1 || Very bright || Large Deflection ||
 * 2 || Medium brightness || Medium deflection ||
 * 4 || Very dim || Small deflection ||

Conclusion: My hypothesis was correct. The overall resistance became higher with each additional bulb, and so the bulbs got noticeably dimmer. In addition, the compass deflected less and less with each additional bulb, which means that the flow rate decreased with each additional bulb as well. The higher resistance caused the flow rate to be smaller, which caused the bulbs to be dimmer.

6.
Problem Set: Resistance





8.
Reading and Questions: [|Pressure Difference]





9.
Notes/Activity: [|Color Coding]









10.
Practice Set: [|Color Coding]





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



Hypothesis: The current and resistance will not be affected.

Data:

1 Bulb 2 Bulb 3 bulb

Observations: - Same brightness - Same deflection

Conclusion: My hypothesis was correct. No matter how many bulbs were placed side by side, they were all the same brightness. Also, in all cases the compass deflected the same amount. Because when bulbs are placed side by side in a circuit, the pressure difference across each bulb will be the same. This means that the same amount of current will be flowing through each bulb.

12.
Does adding wires in series or in parallel effect the overall resistance of the circuit?



Hypothesis:

Adding wires in series will have no effect. Adding wires in parallel will reduce the overall resistance of the circuit.

Data:

Circuit A

Circuit B

Circuit C

Observations:

- Circuit A will serve as a comparison for B and C - Compass deflected the same amount in Circuit B as in Circuit A - Compass deflected slightly more in Circuit C than in Circuit A - In Circuit A, the second bulb went out and the first bulb got brighter.

Conclusion:

My hypothesis was correct. Adding a wire in series has no effect on the resistance because the compass deflected the same amount, so flow rate did not change. This means that wires essentially have zero resistance. However, adding a wire in parallel decreases the overall resistance. Because the wire has no resistance, charge will take the path of least resistance and bypass the second bulb. Because charge no longer passes through the second bulb, the resistance is much lower, and the first bulb lights much brighter and the compass deflects more because the flow rate is now greater.

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



Hypothesis: Since in each circuit the positive terminal of the batteries are facing the same, but opposite, directions, their voltages will cancel out. If a 4.5 volt power cell is dueling a 3 volt power cell, the effective voltage throughout the circuit will be 1.5 volts. If batteries are in parallel with each other, the effective voltage will be the sum of the two voltages. In series, the bulbs will dim and in parallel the bulbs will become brighter.

Data:

Circuit A



Circuit B



Circuit C



Circuit D



Circuit E



Circuit F



Circuit G



Observations:

- Circuit A will serve as a point of comparison - Bulbs in Circuit B light with the brightness of two batteries - Bulbs in Circuit C light with the brightness of one battery - Bulbs in Circuit D do not light; light with the brightness of zero batteries - In Circuit E, the batteries in series act as a 4 cell batter pack. Bulbs light with the brightness of one battery. - In Circuit F, bulbs do not light. The parallel battery pack has no effect - In Circuit G, bulbs light with the brightness of two batteries. Parallel batteries have no effect.

Conclusion: My hypothesis correct for dueling batteries in series, but incorrect for dueling batteries in parallel. In series, the batteries cancel each other out and the difference between the two voltages will be the effective voltage for the circuit; the bulbs dim. However, in parallel, extra battery packs have no effect on the brightness of the bulbs.

14.
Practice Set: [|Battery Structure]







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



Hypothesis: The flow rate will be at the rate the highest resistor allows. The pressure difference across the long bulb will be much higher than the pressure difference across the round bulb. The more resistant bulb, the long bulb, will be much brighter than the less resistant bulb, the round bulb. If we were to color code the circuit above, A would be red, B would be green, C would be blue.

Data:

Without Capacitor



With Capacitor

media type="file" key="Movie on 2011-11-06 at 11.06.mov" width="300" height="300"

Observations:

- Long bulb is very bright, round bulb very dim in the circuit without capacitor. - During charging round bulb briefly lights. When charging finishes long bulb lights and round bulb is very dim.

Conclusion:

My hypothesis was correct. The long bulb has the highest resistance, so the current flowed at the rate the long bulb allowed; the long bulb was very bright, as a result, and the round bulb was extremely dim, if not lit at all. During the charging phase of the capacitor, the current bypassed the long bulb and went straight to the capacitor, because it has less resistance. During this time, the round bulb lit briefly until charging was done, at which point the long bulb lit again and the round bulb dimmed or went out. My hypothesis for the pressure difference at each point was also correct. There is a much higher jump in pressure from point A to point B than from point B to point C; red to green as opposed to green to blue. As a result, the long bulb will be much brighter because there is a great pressure difference across it.

16.
Reading: [|Mixing Bulbs]







17.
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.



Hypothesis:

Adding another round bulb in parallel will have no effect.

Data:

Without extra bulb in parallel

With extra bulb in parallel

Conclusion:

My hypothesis was incorrect. The current splits in half when it reaches a junction in a parallel circuit, so there was much less current going through the two bulbs in parallel. As a result, flow rate decreases for the parallel bulbs causing them to dim. Because the two parallel bulbs are now very dim, very little current is flowing through them, therefore a smaller amount of charge is being resisted than before. This decrease in overall resistance, causes flow rate to increase for the bulbs in series, making them brighter.

18.
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.



Hypothesis: In Circuit 1, flow rate will increase causing the round bulb to become slightly brighter. In Circuit 2, flow rate will increase causing the round bulb to become brighter and the long bulb to dim a little. In Circuit 3, the flow rate will increase, causing the round bulb to become even brighter and the long bulb will go out.

Data:

Pre-Parallel @ A

Pre-Parallel @ B



Circuit 1 @ A



Circuit 1 @ B



Circuit 2 @ A



Circuit 2 @ B



Circuit 3 @ A



Circuit 3 @ B



Observations:

- Use Pre-Parallel data as a point of comparison

- In Circuit 1 with the long bulb in parallel, the round bulb got slightly brighter (it wasn't lit at all before). The compass deflected more in points A and B than in the pre-parallel circuit. - In Circuit 2 with the round bulb in parallel, the first round bulb got significantly brighter and the first long bulb dimmed. The compass deflected even more in points A and B - In Circuit 3 with the shorted wire, the round bulb got very bright and the long bulb went out completely. The compass deflected the most.

Conclusion: My hypothesis was correct. The addition of another branch in parallel increases flow rate, since the compass consistently deflected more and more with every addition, and the first round bulb got brighter with every addition. The flow rate is greatest when the resistance in the added branch is the least, ie. the shorted wire. The long bulb went out because the charge took the path of least resistance and bypassed the long bulb completely.

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



Hypothesis:

a) the flow rate through the batter will increase b) the pressure difference across the battery will remain the same c) the brightness of the left bulb will decrease

Data:

Initial deflection before addition of branch

Circuit A

Circuit B

Circuit C

Observations:

- Use initial circuit before addition of branch as point of comparison - In Circuit A, compass deflected more and the left bulb dimmed slightly - In Circuit B, compass deflected more than in Circuit A and the left bulb dimmed a little more than in Circuit A - In Circuit C, compass deflected the most and the left bulb dimmed further

Conclusion:

My hypothesis was correct. Flow rate increased because adding parallel branches reduces the overall resistance. This was proven by the compass deflecting more and more when a branch with less resistance was added. The pressure difference across the battery never changes according to color coding - positive is red and negative is blue. The left bulb dimmed each time because current takes the path of lease resistance; each additional branch lowered the resistance so more current went there and less to the bulb causing it to dim.

20.
Practice Set: What determines [|Pressure in the Wires]?





21. Ammeter and Voltmeter Lab
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.

Hypothesis/Data:





B. Rank each of the following circuits in terms of flow rate through the battery. E>A>C>D>F>B>G>H

__Analysis__



Discussion Questions:





Conclusion:

In series, the sum of the voltages of each resistor is equal to the voltage of the battery. In parallel, the voltage in each branch is equal to the battery. In series, the current in each wire is equal to the current in other wires. In parallel, the sum of the currents in each branch is equal to the current in the trunk wire or the wire directly connected to the battery.

22.
T/F: [|25 Statements]