Resistors in Series and Parallel Lab

Resistors in Series and Parallel Lab

Set-up	V1	V2	V3	I1	I2	I3	VT
1	5.5			5.9			5.5
2	3	3		3	3		6
3	2	4		2	2		6
4	5	5		6	6		6
5	5.5	5.5			6		6
6	3	2	3	2	2	3	6
7	4	2	5.5	2	2	7	6

Calculations:

1) It = Vt/Rt = 5.5/100 = 0.055 A
    Vt = (It)(Rt) = (0.055)(100) = 5.5 V

2) It = Vt/Rt = 5.5/200 = 0.0275 A
    V1 = (It)(R1) = (0.0275)(100) = 2.75 V
    V2 = (It)(R2) = (0.0275)(100) = 2.75 V
    Vt = V2 + V1 = 2.75 + 2.75 = 5.5 V

3) It = Vt/Rt = 5.5/320 = 0.0172 A
    V1 = (It)(R1) = (0.0172)(100) = 1.72 V
    V2 = (It)(R2) = (0.0172)(220) = 3.78 V
    Vt = V2 + V1 = 3.78 + 1.72 = 5.5 V

4) I1 = V1/R1 = 5.5/100 = 0.055 A
    I2 = V2/R2 = 5.5/100 = 0.055 A
    V1 = (It)(R1) = (0.055)(100) = 5.5 V
    V2 = (It)(R2) = (0.055)(100) = 5.5 V
    Vt = V2 + V1 = 5.5 V

5) I1 = V1/R1 = 5.5/100 = 0.055 A
    I2 = V2/R2 = 5.5/220 = 0.025 A
    V1 = (I1)(R1) = (0.055)(100) = 5.5 V
    V2 = (I2)(R2) = (0.025)(220) = 5.5 V
    Vt = V2 + V1 = 5.5 V

6) I1 = V1/R1 = 5.5/100 = 0.055 A
    I2 = V2/R2 = 5.5/220 = 0.025 A
    It = Vt/Rt = 5.5/168.75 = 0.033 A
    1/Req = (1/R1 + 1/R2) + 100 = (1/100 + 1/220) + 100 = 168.75 Ohms
    V1 = (It)(R1) = (0.033)(68.75) = 2.268 V
    V2 = (It)(R2) = (0.033)(100) = 3.3 V
    Vt = V2 + V1 = 5.5 V

7) I1 = V1/R1 = 5.5/220 = 0.025 A
    I2 = V2/R2 = 5.5/100 = 0.055 A
    It = Vt/Rt = 5.5/76.2 = 0.0722 A
    R3 = R1 + R2 = 100 + 220 = 320
    R4 = 100
    1/Req = 1/R3 + 1/R4 = 1/320 + 1/100 = 76.2 Ohms
    V1 = (It)(R1) = (0.025)(220) = 5.5 V
    V2 = (It)(R2) = (0.055)(100) = 5.5 V
    Vt = V2 + V1 = 5.5 V

Conclusion

• evaluate the differences between theoretical and experimental values.  The agreement is expected not to be perfect, but you should determine if the agreement is reasonable

The theoretical values are the values that in theory you "should" get, if you plug the values into an equation.  The experimental values are those we actually got doing the lab.  In theory, the theoretical and experimental values should be the same, but this will almost never happen due to human error.  In our case, the experimental values was generally a bit less than the theoretical ones.

• make some general statements of what you learned about circuits in series, parallel, series-parallel, and parallel-series networks.

I learned that during a series circuit, the voltage will be constant throughout.  And in a parallel circuit, the voltage will evenly split between the two parallels.  I also learned that in series-parallel and parallel-series circuits, the voltage can differ between the resistors, they aren't necessarily the same for each resistor.  

• discuss other sources of error such as the effect of adding a voltmeter and ammeter in a circuit and not including the internal resistance of the battery in your calculations. 

We found it very difficult to construct the more complex circuits, and then even more difficult to add the Voltmeter and Ammeter to those to find their readings.  There was also much possible human error by the placing of the metal clips.  It made a difference of where on the resistor you placed the clips.  It was also very possible to misread the Voltmeter and Ammeter.  There was much potential human error in this lab.

Water for Elephants Blog

Come on Sarah...

"So what if I'm ninety-three?... why the hell shouldn't I run away with the circus?"

         Well Jacob, it's actually pretty simple why you shouldn't.  You're a ninety-three year old Grandpa.  You can barely get out of bed.  You need a walker to move, and even with that you have trouble just getting down to the dining hall.  Who knows what's in the pills your doctor is feeding you, and your negative physical symtoms would likely ascend away from the elderly home.  On a non-physical side, you have a family Jacob.  How would your family react to a call from the home, "Excuse me, Mr. Jankowski, we regret to inform you that your father has somehow left our campus.  Also, the police have discontinued their search."  How do you react to that?  "Oh, OK!  Hopefully he comes around soon.  Thanks!"  No, that's not what you'd say.  There would probably be no reaction at all.  If you were Jacob's son, you would simply hang the phone up and call the first lawyer that comes to mind.  Because no elderly home just has patients go missing.  

          So say we get past and accept the bitterly unrealistic idea that Jacob stopped being searched for and he continued with the circus.  How would he adjust?  It's pretty blatant that he wouldn't do his duties.  First of all, Jacob can barely remember his own age, so how could he possibly do the math in selling tickets at the booth?  Jacob has a tendency to fall asleep at random times and even talk in his sleep.  A ticket seller is one of the many jobs in the circus where falling asleep on duty isn't going to pass.  The main reason why Jacob was given a job opportunity is because Jacob has circus experience and fantastic stories.  However, Jacob was a veterinarian, which is a bit different from selling tickets.  Also, no one in the ticket line is going to be too thrilled about a customer listening to one of Jacob's circus stories during their transaction.  

         According to a critic on www.bookbrowse.com, "The book ending was a little too cheerful to be believed..."  The book ending was very cheerful.  The reader grew a bit depressed when Jacob realized his family forgot about him on this special circus day, but the conclusion of Jacob getting a new job attempted to lighten things up.  Obviously, this will please some readers who are giddy for a happy ending, but it won't fly with the critics.  Perhaps Gruen could have done her ending differently by keeping the conversation with the circus director, but concluding during their conversation and without the job offer.  I'm sorry Jacob, I really am, but no ninety-three year old is going to run away and be forgotten by their nursing home or family.  This is the twenty-first century, not the Great Depression.

Electric Field Hockey Post-Game Analysis

1. Which direction do electric field lines point for positive charges?

Electric field lines (protons) always point AWAY from positive charges.

1. Which direction do electric field lines point for negative charges? 

Electric field lines (protons) always point TOWARDS positive charges.

1. What do the direction and strength of the field lines indicate for the (positively charged) “puck?” 

The direction and strength of the field lines in this simulation represent where the puck will travel.  For example, since the puck itself is positive, if you put a proton next to it, the puck will travel in the opposite direction because only opposites attract.  The closer the proton is to the puck, the farther the puck will travel.  If a electron is put near the puck, the arrow will point towards the electron because the puck and electrons attract.

1. Did the (positively charged) puck always move in the same direction as the field lines it was passing over? 

No.  If the field lines are all pointing inwards toward a specific electron, then it will have an effect on the puck.  But if the puck is already traveling with a great force (caused by a proton pushing it away) then the puck will make a circular motion around the field lines.  So even though the field lines point downwards, the puck will travel across them (caused by the proton) but eventually end up where the field lines are pointing.

1. What happened (or would happen) if you changed the charge of the puck from positive to negative? 

The puck would react just the opposite as before.  Putting an electron next to the puck would make the puck repel, while putting a proton near the new puck would attract it.

1. What happened when you increased the mass of the puck?
   

As the mass of the puck increases, the acceleration decreases.  This is modeled by the equation: Fnet = mass x acceleration.  So when the mass goes up, the acceleration must go down in order to keep the force the same. 

7. How did the distance between the puck and the particles affect the motion of the puck? 

The closer the puck is to the particles, the greater the attraction.  So when a proton is put very close to the positive puck, then the puck will repel very quickly and with lots of force. On the other hand, if a proton is put far away from the puck, it will only have a weak reaction on the puck and the puck will barely repel.

7. List two or three cool things you got the puck to do. Why did each one happen?
   

1) I could make the puck simple bounce around and into the goal without using any electrons.  I did this by first putting a proton near the puck, then putting a row of protons on top and to the right of the puck, so it would bounce off (be repeled).  Then I had the puck bounce of another row of protons which were lower. Then the puck entered the goal.

2) I could make the puck stand still by simply putting a proton and electron next to the puck.  The electron and proton neutralized each other, and the puck stood still.

9. The field lines on the program are evenly spaced, with darker shades of grey indicating a stronger field. This is a very clear way of presenting this information. However, it is not what we will normally use. Why do you think that is? 

Most of the field lines we use in Physics are hand drawn.  It is difficult to make different shades on paper using a pencil or pen.  It's easier to notice a difference in the strength of the fields by using different lengths of arrows.

Columbine: Golden Quote #2

A Columbine killer pointed his gun at Cassie Bernall and asked her the life-or-death question: 

"Do you believe in God?"

She paused. The gun was still there.  "Yes, I believe in God," she said.

That was the last thing this 17-year-old Christian would ever say.

                 A short while after the massacre at Columbine, Cassie's parents appeared on Oprah to discuss their daughter's unbelievable courage.  At one point, Oprah poised the question, "Do you wish she has said 'No'?"  The mother had mixed feelings.  There had been an account by another girl at the school who had begged a shooter for her life and he ended up letting her live.  So on one hand, Cassie's mother wishes she had begged, for the chance that she too but might have been spared.  But on the other hand, Mrs. Bernall admits that there is probably "no more honorable way to die" than to profess your faith in God.  I come from a Christian family so I was curious to ask my mom what she would have wanted me to do if I were in Cassie's situation.  She told me she would have wanted me to do what Cassie did, profess my faith in God, rather than deny Him for the chance at not being shot.  I told her that wasn't an answer most mothers would give but she told me, "I would see you again in Heaven."

                 Now lets look at the possibility if Cassie had answered the question differently.  Cassie could have ignored the question altogether, and begged for her life.  My guess is the shooter would continue to press her for an answer, and if she didn't give one, he would shoot her.  I am guessing that the killer who had questioned Cassie was Eric.  My reasoning for this is that Dylan wrote about God a lot in his journal, and constantly restated that he did believe in God.  However, as time went on and his social-outcast life kept turning for the worst, he got angrier and angrier at God, who he thought was being completely unfair to him.  So if he had asked Cassie the question, I don't think he would have shot her for answering "yes," because he believed in God too.  So it must have been Eric.  Now lets imagine if Cassie had answered "no" to the question.  The shooter might have been pleased with this answer and let her live.  If he had let her live, Cassie would live with regret for the rest of her life that she had denied her Lord and might even wish she had said yes.  There is also the good possibility that even if Cassie had said "no," the shooter still would have killed her.  Cassie believed in a literal Heaven, so it probably ran through her head at that moment that if she said no, and the killer still shot her, God might punish her by not sending her to Heaven.  So if we were somehow able to communicate with Cassie now, I'm sure she would not regret answering "yes" to the killer's fatal question.

                If we were to agree on the idea that Cassie's killer was in fact Eric, not Dylan, then we need to ask the question of why he didn't believe in God?  Eric's family used to belong to a Evangelical church, but they weren't very involved and ceased their attendance about five years before the massacre.  So Eric had at least somewhat grown up around the idea of an existing god.  But another phenomenon to look at is the fact that Eric saw himself as superior to pretty much everybody around him.  He bragged about this on his online Blog site and his personal journal.  He wondered why everybody around him was so stupid, and he loved the idea of natural selection.  So there is a good chance that Eric didn't believe in God simply because he couldn't accept the fact that there was somebody superior to himself. Maybe he wanted Cassie to say she didn't believe in God because he wanted her to praise him or something.  Maybe that's what he did to the girl who had to beg for her life (this is assuming it was also Eric dealing with that girl).

              All in all, even if you aren't a Christian, we can all agree that Cassie had an honorable death because she stood up for what she believed in.  No matter what it may be that you put your complete faith in, you should stand up for it, even in the most extraordinary circumstances.