Introduction: (Initial Observation)
“Static electricity” sparks can be irritating and their cause sometimes seems mysterious. Most people have encountered painful car-door sparks, as well as those wintertime sparks from doorknobs and large metal objects. What causes these? What can be done to stop them? and which material can be charged with static electricity?
The aim of this study is to examine different material to see which material can be charged with static electricity.
Experiments 1 and 3 are required for this project. All other experiments and samples are optional or you may try them as a hobby.
Information Gathering:
Find out about static electricity. Read books, magazines or ask professionals who might know in order to learn about the causes and effects of static electricity. Keep track of where you got your information from.
What is conductivity?
Conductivity is the ability to conduct or transmit electricity. The word conductivity may also be used in relation to transmitting heat and sound.
Initial Experiment
Demonstrate static electricity
Cut a piece of paper to small pieces and place them on a glass or wooden table.
Cut a plastic comb and use it to comb your dry hair for about 10 seconds
Hold the comb above the pieces of paper.
Papers will move, stand up and pulled up by the comb. This shows that the comb and papers contain opposite charges of static electricity.
Would you get the same result with a wooden comb?
If you like to get your information from the Internet, see Humans and Sparks as a good start.
To create static electricity and see it’s spark, see Big Sparks With A Ridiculously Simple Electrophorus. Here you can find a simple method of producing relatively large amount of static charge.
As you may already expect, static electricity also creates problems. Many of the companies who manufacture ant-static chemicals, promote their products by explaining the benefits of anti-static material and hazardous of static electricity. Following are some of the problems that are associated with static electricity:
– handling problems during transport, storage and packing
– dust contamination, affecting both appearance and performance of end-products
– risk of electrical shocks to employees working at the machines
– risk of electrical discharge causing fire or explosion
Antistatic agents act to reduce surface resistivities and hence dissipate high electric charge densities on the surface of plastics.
Electrostatic charges are generated by frictional contact between two materials with different susceptibilities to electron loss. One material loses electrons and becomes positively charged. The other gains electrons and, with them, a negative charge.
When we rub two different materials together, which becomes positively charged and which becomes negative? Scientists have ranked materials in order of their ability to hold or give up electrons. This ranking is called the triboelectric series. A list of some common materials is shown here. Under ideal conditions, if two materials are rubbed together, the one higher on the list should give up electrons and become positively charged. You can experiment with things on this list for yourself.
The cause of unexpected doorknob sparking only seems mysterious because of a misconception. As children, most of us learn the trick of scuffing our shoes across the carpet in order to charge our bodies. Then we go to search for victims to “zap” with our electric fingers. Sparks from rug-scuffing are familiar. If you scuff your feet on the carpet, you expect to be zapped by the next doorknob you touch. But why do our bodies sometimes become charged from simply walking around?
Two different electroscopes; one
uncharged, the other positively charged. Source
TRIBOELECTRIC SERIES
Air (*?)
Human Hands Most Positive
Asbestos
Rabbit Fur
Glass
Mica
Human Hair
Nylon
Wool
Fur
Lead
Silk
Aluminum
Paper
Cotton ZERO
Steel
Wood
Amber
Sealing
Wax
Hard Rubber
Nickel, Copper
Brass, Silver
Gold, Platinum
Sulfur
Acetate, Rayon
Polyester
Styrene (Styrofoam)
Orlon (acrylic fiber)
Saran
Polyurethane
Polyethylene
Rubber balloon
Polypropylene
Vinyl (PVC)
Silicon
Teflon Most Negative
Question/ Purpose:
The purpose of this project is to see which materials can be charged with static electricity.
Identify Variables:
Many variables may affect the static electricity charges. These variables are: The amount of moisture in the air. The temperature. conditions of frictional contact. Type of material. Insulation level of material.
In this project we will only study the type of material. We will attempt to maintain all other conditions unchanged during our experiments. So the only independent variable is the type of material.
We want to see which materials can be charged with static electricity, so chargeability or the amount of charge is the dependent variable.
Hypothesis:
My hypothesis is that the material that are not conductive such as plastic and paper can be charged with static electricity. Conductive material will transfer their charges easily and will not remain charged. However they are a way of discharging static electricity specially when they are grounded.
(grounded = connected to ground)
Experiment Design:
In order to see which material can be charged with static electricity, we first need a device to test, identify or measure static electricity. such device is called electroscope and can easily be made.
Experiment 1: Make an Electroscope
Materials:
-
- Glass Jar or Glass
- Aluminum Foil
- Index Card
- Paperclip
- Tape
Background:
An electroscope is an instrument for detecting the presence of static electricity. It consists of two thin metal leaves suspended from a metal hook. When the hook is brought near a source of static electricity, some of the electrons in the hook are pushed to the leaves (if the source is negative) or pulled up to the hook from the leaves (if the source is positive). Either way, the leaves are now charged the same way as each other and so they repel each other. The amount they open up is proportional to the charge of the source (if the sources are always held at the same distance from the hook).
Procedure:
Cut two strips of foil 1cm by 4cm (1/3″ by 1 1/2″).
Open out the paperclip to form the L shape, or the hook shape. Push the hook through the middle of the index card and tape so that it is at right angles to the card. Lay the two foil strips on top of one another and hang them on the hook by pushing the hook through them.
Lay the card over the jar so that the strips hang inside (see picture below).
Charge different material by rubbing them against your hair or a wool or nylon fabric.
Bring various charged objects near the top of the hook and observe what happens. Notice what happens to the strips when the sources are removed. Does anything different happen if the source actually touches the hook? If the strips do not fall back together, gently touch the hook with your finger or a water pipe.
Another method of hanging the foil to the L shape hook is to fold the strip of foil and hang it over the lower part of the L. This will only work if your foils are really thin and flexible.
This method is used in the following sample.
You may modify this design and procedures as you need. Following are some actual images of this experiment.
I received a gift and saved it’s wrapping material. These material are some kind of plastic coated with a thin layer of aluminum. They have a nice metallic look. They are known as “Mylar”
To make my electroscope I used two strips of these wrapping foils, a paper clips that I formed like the letter L and some adhesive tape. First I used a small piece of tape to connect two strips together. Then I used another pieces of tape to connect the strips of foil to the paper clips.
This is the final result. I could use it like that; however, I decided to place it in a glass jar for better results.
I passed the paperclips through a piece of cardboard and then placed it on a glass jar.
Initially two strips are attached.
Then I charged a plastic comb by rubbing it to my hair and moved it close to the paperclip. Foil strips moved apart.
I tested rubber balloons, glass test tube, PVC pipe, wood dowel, polyethylene jar, Styrofoam cup and many other objects. Each of these material could force a foils to move apart depending on their accumulated charge.
I used this electroscope to do my main experiment that is comparing different material for their ability to hold static charge. (Experiment 3)
A modified version of Electroscope
Here’s a fun demonstration device to illustrate that like charges repel, and unlike charges attract. I call it a modified electroscope.
Use a 35 mm film canister. Drill a hole that a straw fits snugly through. Wrap it with a small piece of Aluminum foil, shiny side out.
Find the drilled holes by rubbing the fingers over the foil and feeling the dimple of the hole. Insert a pencil to puncture the foil to enable the straw to be inserted.
(Alternative – use a larger piece of foil, roll into a ball, and use a pencil to make a hole through it.)
Make two small cuts in the straw end for the thread to sit in.
Use a packing peanut and tie sewing thread through the hole.
Drill a hole in a small block of wood as shown above. Slip the straw through the foil covered film canister, and position as shown. Tie the thread to the packing peanuts and insert the thread into the cuts made in the straw.
Rub the 12″ long 1″ diameter PVC pipe with a cloth. Charging by rubbing means electrons will leave the cloth, and go to the PVC, leaving it with an excess of minus charges – electrons. Rub the PVC on the foil covered canister, and it will charge negative along with the peanuts. It may require several tries. The peanuts will repel out.
The white PVC plumbing pipe is easily available. The rod becomes charged negative by rubbing with a cloth, a sock, wool or cotton will do fine. The electrons leave the cloth to accumulate on the rod. The cloth is left positive. Rub the rod on the foil slowly, It will charge the the foil and the peanuts negative, and they will repel. Put the cloth up near the peanuts and they will be attracted to it. If you rub a clear plastic rod, acrylic, it will be charged positive. The charge is dependent upon the material used.
Although the electroscope is perfect for identifying the static electricity, you may want to try electronics for this purpose. There are some electrical switches that work based on this method. In other words you will not need to move a lever or push a button, instead you touch a flat metallic surface and the switch will open or close. The following experiment is using a similar method to detect the static electricity.
Experiment 2: (Optional) Electronic Sensitive Charge Detector
This simple circuit can detect the invisible fields of voltage which surround all electrified objects. It acts as an electronic “electroscope.”
Regular foil-leaf electroscopes deal with electrostatic potentials in the range of many hundreds or thousands of volts. This device can detect one volt. Its sensitivity is ridiculously high.
Since static electricity in our environment is actually a matter of high voltage, this device can sense those high-voltage objects at a great distance. On a low-humidity day and with a 1/2 meter antenna wire, its little light will respond strongly when someone combs their hair at a distance of five meters or more. If a metal object is lifted up on a non-conductive support and touched to the sensor wire, the sensor can detect whether that object supports an electrostatic potential of as little as one volt!
PARTS LIST:
-
- 1 – Standard 9-volt battery
- 1 – MPF-102 N-channel Field Effect Transistor (FET) Radio Shack #276-2062
- 1 – Red Light Emitting Diode (LED) Radio Shack #276-041
- MISC:
- Battery connector (#270-325)
- Alligator Clip Leads (#278-1156)
- solder, if desired
- 1-meg resistor (optional)
- plastic, fur, foil, comb, tape dispenser, plastic cups for test
(Tiny version built on top of a 9v battery connector)
CONSTRUCTION HINTS
Warning: don’t connect the battery until you are SURE you’ve hooked everything up exactly right. It’s possible to burn out the FET or the LED if they are connected incorrectly. Don’t let the transistor’s wires bump together even briefly, or it will flash the LED and burn it out.
NOTE: Don’t ever connect any LED directly to a 9-volt battery, it will burn out the LED. A bare LED needs a 1000-ohm resistor wired in series to limit the maximum current from the 9-volt battery.
Warning: Avoid touching the Gate wire of the FET. Small sparks jumping from your finger to the Gate wire can damage the transistor internally.
The 1-meg resistor helps protect the FET from being harmed by accidental sparks to its Gate lead. The circuit will work fine without this resistor. Just don’t intentionally “zap” the Gate wire.
To test the circuit, charge up a pen or a comb on your hair, then wave it close to the little “antenna” wire. The LED should go dark. When you remove the electrified pen or comb, the LED should light up again.
IF IT DOESN’T WORK, the humidity might be too high. Or, your LED might be wired backwards, or the transistor is connected wrong, or maybe your transistor is burned out. Make sure that the transistor is connected similar to the little drawing above. Also, if the polarity of the LED is reversed, the LED will not light up. Try changing the connections to your LED to reverse their order, then connect the battery and test the circuit again. If you suspect that humidity is very high, test this by rubbing a balloon or a plastic object upon your arm. If the balloon does not attract your arm hairs, humidity is too high.
This FET sensor is not an ideal educational device because it responds differently to positive than to negative Potential Difference at it’s “Gate” wire.
Experiment 3: (Main Experiment) Testing material for their potential to be charged with static electricity
Materials and Equipment:
You will need your electroscope and some of the following material for test.
-
- PVC pipe
- polyethylene plastic bag
- Silk
- Wood
- Plastic comb
- Metal spoon
- plastic cup
- Fur
- Aluminum Foil
- Cotton fabric
- Polyester fabric
- Paper
- Ceramic
- wool
- Rubber
- Any other item (Get idea from TRIBOELECTRIC SERIES table)
Procedure:
Setup your experiment close to a water pipe, so you can discharge the static electricity of your body with the pipe as needed. Also discharge every test item by touching it to water pipe right before testing it. (It must be a copper pipe or a faucet.)
Start with a woolen fabric and rub it against any item of your choice for 30 seconds. While having both items in your hand, take them close to your electroscope one at a time to see if they are charged and how much. You can visually decide how much do the leafs distance each other and use it to rate the amount of static electricity charged in each object. If you are testing 10 items, at the end you will have a table like this. The numbers in the table can show how many millimeters did the leafs distance each other.
| Wool | Fur | Nylon | Wood | PVC | Aluminum | Steel | Silk | Paper | Ceramic | |
| Wool | ||||||||||
| Fur | ||||||||||
| Nylon | ||||||||||
| Wood | ||||||||||
| PVC | ||||||||||
| Alum. | ||||||||||
| Steel | ||||||||||
| Silk | ||||||||||
| Paper | ||||||||||
| Ceramic |
Note that Items that you rub to each other will collect opposite charges. For example when you rub a PVC pipe to a woolen fabric, they are both able to show static charge in your electroscope, however when one of these touches and charges your electroscope, the other is able to discharge your electroscope.
How do I know if something is charged Positive or Negative?
Material that can be charged by rubbing them against wool, hair or nylon will have negative charges.
Material that can be charged by rubbing them against polyester, will have positive charge. So you can measure the maximum charge and identify the type of charge that a substance will collect.
Following is a sample result.
| Material | Static charge | Charge type |
| Wool | 6 mm | + |
| Silicon | 21 mm | – |
| Nylon | 7 mm | + |
| Wood (Wood dowel or wooden stick) | 2 mm | – |
| Cotton | 0 mm | |
| PVC (PVC pipe used for plumbing) | 20 mm | – |
| Aluminum | 2 mm | + |
| Polyester | 12 mm | – |
| Steel | 1 mm | – |
| Silk | 3 mm | + |
| Teflon (available at hardware stores) | 22 mm | – |
| Glass | 11 mm | + |
You can decide your own type of material for test and it does not have to be 10. Any number of test items from 7 to 15 is is good for this project. You can use your results to make a bar chart.
Additional Optional Experiments
Super Cheap Instant Static Generator
PVC tubing with some fur, wool, paper towel, chamois, or other material wrapped around.
The way this works is very simple. The tube is held in one hand, while the other hand slides the fur back and forth along its length. 1/2″, 3/4″, and 1″ PVC pipe all work, but you need at least a two and a half foot long section (three foot section is even better).
In the photo above the fur is surrounded by a short piece of foam pipe insulation held on by a rubber band. This makes sliding it back and forth a little easier. If you do this make sure that your skin touches the fur or cloth somewhere. In theory the fur is leaving electrons on the tube. You will be able to leave more electrons (generating a stronger charge) if the fur can replace electrons it has lost by getting them from your body.
Benjamin Franklin used a tube similar to this when he first started experimenting with electricity. His tube was glass, but the operation was the same.
The electrostatic generator needs a place to store and build up an electric charge. Without the capacitor, a static generator such as the one made with PVC pipe would have to be operated in a very dark room in order to see any sparks produced. The capacitor stores up enough of a charge to make a very visible spark in broad daylight and, can also be heard.
The picture of the film can leyden jar is self explanatory. Now days, a film “can” is really plastic but it is a kind of plastic that makes a great capacitor. The inside foil can be taped to the wall or secured any way you want, so long as it makes good contact with the wall. One person wrote back and reported that the film can exploded as a result of using rubber cement to glue the inside foil to the wall. Rubber cement is highly flammable and explosive and was set off by sparking inside.
Materials and Equipment:
List of material can be extracted from the experiment section.
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
Calculations:
No calculation is required for this project; however, you may need to measure the distance between the foils.
To do that you must have ruler that can measure millimeters. Then you can visually estimate the distance of the foils by comparing that distance with the ruler.
You can also place the ruler behind the foil (behind the jar) so you can see. Finally you may use a copy machine to make a photocopy of such a ruler and put a piece of that inside the jar.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical
Conclusion:
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
Question: I’m still uncertain about how to tell the charge of an item – whether it is positive or negative. In the info you provided before, you stated that “material that can be charged by rubbing against wool, hair, or nylon will have negative charges. Material that can be charged by rubbing against polyester will have positive charges.” How do you know this? Is it based on the ranking of these materials on the Triboelectric Series, with wool, hair, and nylon having positive charges and polyester having a negative charge, according to the Series? What if you rub nylon and aluminum together? What would their charge be because both are listed as positively charged on the Triboelectric Series? My guess is that two items with the same charge would not create a charge; is that the case? Also, if the leaves on the electroscope spread apart, does this always mean that the item contacting the electroscope is negatively charged? As you can see, I am confused about this. Thanks for your help.
Answer: Static electricity is generated by unbalancing the molecular construction of relatively non-conductive insulators such as plastics and paper. All matter is composed of atoms. A balanced atom contains positive charges that are present in the nucleus of the atom. An equal amount of negative charges orbit this nucleus in the form of electrons. Both charges are equal and, therefore, the overall charge of a balanced atom is zero. However, should this configuration be disturbed and several electrons removed from this atom, we end up with a greater positive charge in the nucleus and a deficiency of electrons, which gives you an overall charge in the positive direction. Conversely, should we add a few extra electrons, we have an overall charge of negative, due to the fact that we now have an excess of electrons and the net charge is now in the negative direction.
To accurately measure the type and the strength of an electrostatic charge, you may use a static meter. Static meters are usually able to show the static charge in an object in a range of -20000 volts up to +20000 volts without touching the object.
The Triboelectric series only shows the relative tendency of material to get charged by static electricity. If you rub nylon and aluminum together, you will still build up some small charges. In this case nylon becomes more positive and aluminum becomes less positive. This happens because nylon is an insulator. If you rub aluminum and lead, they don’t buildup any charges because they are both conductive and balance the charges among themselves.
When the leaves of electroscope spread apart, that means that they have charges. The rule is that same type charges repel each other. Electroscope leaves are connected to each other; so they always have the same type of charge (if any). Electroscopes will only show the presence and the strength of a charge. They don’t show whether it is positive or negative.
Possible Errors:
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.
