Electrostatics Lab Summaries



Sections 1.1-1.2

In the first lab we first used a piece of plastic tube and attempted to attract ripped pieces of papers. This failed since they both were neutral. However after rubbing the tube with fur, the tube became charged from the neutral fur. Now the tube was able to attract pieces of paper, but only at a close distance. This proved that electrostatics force is bigger than gravity, since it was able to attract the pieces of paper. However this experiment is possible even with a pen or a comb since the neutral fur, is able to transfer or remove neutrons from the fur. Which makes the object a positive charge or a negative charge since the unbalanced amount of neutrons in the object.The second part of the lab was a commentary discussing this new electrical charge force that does not require touching the object in order to put the force on the object. The only other force like this is gravity. This force is dependent on distance - the smaller the distance between the object, the stronger the force. For example, with the tape scenario, the closer you put the two pieces of tape together, then repel each other more strongly when brought closer together.

Sections 1.3-1.4

In sections 1.3 we focused on using a tool made up of a pie tin and a Styrofoam cup. The Styrofoam cub was glued it the pie tin and used like a handle. We started off by doing the same experiment as with the plastic tube in section 1.1 and 1.2, we rubbed the tin gently with a piece of fur and attempted to pick up little pieces of paper. When the tin was placed over the paper we recognized that it didn't pick up the papers there for we could conclude that the pie tin was not charged by the fur. Luckily for us Mr. Rylander introduced to us a new tool for us to use; a Van de Graaf. This device makes its own electrical charge and can be used to charge other objects. Than as instructed we held the pie tin by the Styrofoam handle and touched the pie tin to the metal sphere of the Van De Graaf. To test if the pie tin was charged we proceeded to touch the pie tin and received a shock telling us that the pie tin is in deeded charged after touching the Van De Graaf. Not only is the place were the tin touched the Van De Graaf charged but the whole tin became charged and shocked you no matter were you touched it.When we tried to charge the plastic tube we found out that when touching it with our hands it did not shock us and when tried to pick up pieces of paper with the object we had no luck. From both of these instances we concluded that the tube did not have a charge or at least release the charge. We then tried it with the pie tin and in fact it was the exact opposite of the rubber tube. It gave us a shock that took away all of its charge leaving it charge less. This experiment showed us the difference between conductors aka the metal pie tin and insulators aka the plastic rod. The conductors allow charge to easily pass through them while the insulators keep the charge in that object. Another difference in conductors and insulators is the method used to charge these two objects. In order to charge a conductor there must be a object (like the Van De Graaf) that has a already made charge, this charge can the easily be transferred to the conductor object so that it is then charged also. A insulator is charged in a way which involve making friction to cause an object to be charged. An example would be rubbing a plastic tube with fur.


Pie Tin
Tube
Charged by Van de Graaf or friction?
Van De Graaf
Friction
Charged over just part or over entire surface?
Entire
Entire
Remains charged after touching or becomes neutral after touching?
Neutral
Charged

In section 1.4 we focused on using tape as a tool. We did a test to see if the tape could actually be charged by friction. To test this we stuck the tape to the table-top and then peeled the tape carefully but fairly fast from the table-top. After doing that we tested to see if it was charged doing the same test from section 1.1 with the plastic tube; we brought the tape close to the pieces of paper and saw that the papers attracted to the charged tape.We know that the tape is an insulator. There are a couple of reasons we know this. One is because the tape was able to be charged and hold the charge within itself, we were able to see this by being able to touch it and keep its charge. Another way is that the tape did not shock us, it created a static friction like the tube, where as the conductor shocked us. After we saw that the tape was charged we wanted to fund out what kind of charge it was, negative or positive. The experiment was that we rolled up a piece of paper into a tube and saw that the tape attracted to the paper tube. From doing this we could tell that one must have a positive charge and the other negative, or that one is neutral ( the paper tube) and the tape is either positively of negatively charged.We know that the paper tube is neutral because it could not pick up pieces of tape like the tape did. This shows that if you find that two things attract it does not necessarily mean that the are both charged.


Sections 1.5-1.6

In this part of the lab we learned the different affects that charged tape has. When we place two strips of tape on top of each other, we learned that the top strip becomes postitvley charged and the bottom strip becomes negitivley charged. The strips therefore

Sections 1.7-1.8

In 1.7 we experimented with the positive and negative charges of objects. By using a negatively charged plastic tube we can figure out the charge of each of the pieces of tape. The bottom piece of tape was negatively charged. We knew this because the piece of tape the negative charge of the plastic tube. This indicates that the bottom piece of tape was negatively charged as well, since similar charges repel. In addition to this by using the negatively charged plastic tube we can figure out that the top piece of tape was charged. As we held the plastic tube to the top piece of tape, the top tape attracted to the plastic tube. Since oppositely charged objects, for example positive and negative, attract we can conclude the top piece of tape was charged. We also did this experiment with a positively charged glass rod. We found that by holding the glass rod to the bottom piece of tape it attracted because opposite charges attract (negative and positive), so this means that the bottom tape is negatively charged. By doing this we also found that the top piece of tape was positively charged because it repelled from the glass rod when it was held in front of the tape, because similar charges repel (negative-negative or positive-positive).
In Section 1.8 we learned about polarized objects. An object is polarized when it has equal amounts of both charges, like being a neutral object. For example; when a negative charge was placed next to a roll of paper the paper acted like a positive charge and attracted, but the roll of paper was also exposed to a positive charge and it acted like a negatively charged item and attracted. So a polarized object is a neutral object that gets attracted to charged objects.


Sections 2.1-2.2

In section 2.1, we learned a new way to charge an object. First, we charged a piece of styrofoam by rubbing it with a piece of rabbit fur. We then placed the pie tin on the styrofoam and when we touched it, we felt a shock. We then picked the pie tin up off of the styrofoam by the cup and touched the pie tin once again. Again, it gave us a shock. We were to repeat this process without re-rubbing the styrofoam with the fur. It seemed as if this could go on forever, but we got to about 47 shocks (without recharging the styrofoam) and decided to quit. In this section, we also got a chance to turn off the lights in the classroom and observe the spark that appears when your finger gets close to a charged object. The spark appeared inbetween the finger and the pie tin, wherever you decided to touch the pie tin. In section 2.2 we learn that charges can not be transferred through differnt objects. Although, charges can exert a force through the insulator. After you rub the stryofoam with fur and put the pie tin on top polarization took place. Polarization is the reallignment of charges in a neutral object when a charged object is brought near. In 2.1 we saw that when you touched the second pie tin, to the pie tin that was sitting on the stryofoam that there was a shock. This is possible because when the stryofoam polarized the pie tin it gave it a positive charge. Then we touched the neutral pie tin to the positive charged pie and it sparked.

Section 2.3 In section 2.3, the materials used were two pie tins attatched to an insulator(styrofoam cup or plastic tube), a flat sheet of styrofoam, and fur. We determined the charge on the styrofoam by bringing it near each test tape. After rubbing the styrofoam with the fur, the styrofoam repelled the negative tape. After this experiment we found out that the charge of the styrofoam was negative. After charging one pie tin and then taking another pie tin and touching it against the first pie tin, we brought it near the test tapes. The pie tin that we were holding while touching the original pie tin repelled the negative tape which meant that it was negatively charged. Finally, we determined that the pie tin(original pie tin) was positively charged because it attracted to the negatively charged tape.