Introduction: (Initial Observation)
As times passes, more and more communication systems use fiber optic cables instead of traditional copper wires. Using optical fiber to transmit sound or data is much more complex than using copper wires. All signals are initially in the form of electrical waves. In order to transmit them through fiber optics, first they need to be converted to light waves. At the destination, a second conversion must be done to change light waves to electrical waves.
Optical fibers are not easy to work with. They require special equipment and trained technicians for cutting and making connections. On the other hand you can cut copper wires with any pair of scissors or pliers and they can be connected easily.
The speed of transmission for light waves and electrical waves is the same.
With so many difficulties in using fiber optic lines and no obvious benefit, why do we use them?
In this project we compare optical fibers with copper wires for transmission of sound or data.
The project number 13 in the Engineering section of Senior Projects contains additional information and experiments that might be subjects of interest to you.
Before starting any scientific research, you must prepare an outline of what you are planning to do. You may later change or update your plant based on the information that you gather.
This is a sample outline or plan for this project.
- Study to find out how signals are transformed from one form to the other. I need to know how sound waves become electrical waves and how electrical waves become light waves. I should also know how light waves are converted back to electrical waves and sound waves.
- Setup experiments to try and observe such transitions and transmissions.
- Find out why optical fibers are a preferred method of transmission.
- Perform experiments to show why copper wires are not the best choices for transmitting signals. The experiment will research the amount of interference that may enter a copper wire in the form of noise.
- Prepare a display to show how electrical waves are being converted to light waves and how they are changed back to electrical waves.
Find out about pros and cons of transmitting signals using copper wires and fiber optics. Read books, magazines, or ask professionals who might know in order to learn about the effect of distance on quality of signals delivered via a copper wire or optical fiber. Keep track of where you got your information from.
The following are samples of information that you may find.
Innovations in optical fiber technology are revolutionizing world communications. Newly developed fiber amplifiers allow for direct transmission of high-speed signals over transcontinental distances without the need for electronic regeneration. Optical fibers find new applications in data processing. The impact of fiber materials, devices, and systems on communications in the coming decades will create an abundance of primary literature and the need for up-to-date reviews.
History of Fiber Optics
Read about the history of fiber optics and learn about John Tyndall’s Experiment.
In 1870, John Tyndall, using a jet of water that flowed from one container to another and a beam of light, demonstrated that light used internal reflection to follow a specific path.
As water poured out through the spout of the first container, Tyndall directed a beam of sunlight at the path of the water. Now the same experiment is being repeated using laser lights. Source…History of fiber optics
Optic Fiber vs. Copper
Optic fiber provides several advantages over copper. Optic fiber does not radiate, and because optic fiber doesn’t carry electricity, optic fiber is immune to electrical interference. Optic fiber is lightweight, flexible, and has become easy to handle and install. Optic fiber installation costs continue to diminish. Also, the life span of optic fiber is longer than that of copper.
Two common questions that are being studied in relation to optical fibers are:
How does distance affect degradation of signals in optical fibers?
How do different fibers vary in their transmission distance or signal degradation?
Researching these questions usually requires a very long optical fiber and high precision test equipment. To simplify these researches, you may substitute a real optical fiber with clear plastic fibers that degrade the light very fast.
Comparison of Optical Fiber to Copper wires is a series of experiments showing that copper wires are susceptible to interference while optical fibers do not have such a problem.
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is:
- To experiment transmission of signals via optical fiber and copper wires.
- Observation and measurement of interference in copper wires that seem to be the most important cause of preferring optical fiber for communication.
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
Problems such as noise, interference and signal degradation multiply for longer distances. So I define variables as follows:
Independent variable is the distance of transmission or the length of wire.
Dependent variable is the amount of interference and noses that enter a copper wire from the environment.
Constants are: Wire type, wire diameter, method, experiment procedures and tools.
Controlled variables are environmental noise generators such as electric motors, radios, televisions, and other electrical equipment. I will make sure that such equipment will stay on or stay off during my experiments.
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.
A longer wire acts like a large antenna and collects more electromagnetic waves or signals from the environment.
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Both fiber optic cables and copper cables are shielded. It is obvious that light cannot pass through the shield; so no external light will interfere with signal lights. For the purpose of your project it is sufficient to show that copper wires are affected by electromagnetic waves.
While speaking with a communication specialist from a local phone company I learned that using optical fibers is a preferred method of transmission because fibers transmit a clearer signal to a longer distance. Copper wires do not transmit a clear signal because they absorb varieties of electromagnetic waves or noises. Electromagnetic waves include radio and television signals as well as those produced by other electrical equipment such as switches and electric motors. Even lightening can result a surge of electricity in wire. In this experiment, I will try to see if copper wires really absorb noises and other electromagnetic signals.
- Get about 5 feet of insulated copper wire.
- Remove the insulation of about one inch of one end of the wire.
- Mount the wire between two spots to resemble electric posts. (or you can simply hang the wire somewhere).
- Get a high precision digital voltmeter and set it to AC volts (AC stands for Alternative Current. Note that all electrical waves are alternative current).
- Connect the black electrode of the voltmeter to the ground (water pipe or faucet are considered ground).
- Connect the red electrode of voltmeter to the ground too (another part of the same pipe). You should read 0 on the voltmeter.
- Then connect the red electrode of the voltmeter to the wire, where you removed the insulation.
- What is the voltage that you read on the voltmeter?
- If you see any number other than 0, it means that the copper wire is getting electromagnetic waves and converting them to electricity.
(Some people call it free electricity. Close to radio/ television stations or antennas, this electricity can be strong enough to light up a small light bulb).
Other Benefits of this experiment:
What you did in this experiment is measuring electromagnetic signals. Scientists have noticed that sometimes large increases in electromagnetic signals are an indication of a pending earthquake. Such increase can start a few minutes up to a few days before the earthquake. Monitoring electromagnetic signals is now one of the tasks performed by geologists to monitor underground activities that may lead to an earthquake or volcanic eruption.
To learn more about this subject, search the Internet with keywords such as “Earthquake and Electromagnetic”.
Comparing noises in different areas
In this experiment you attempt to identify different sources of electromagnetic signals that may enter a copper wire without even touching it.
- Repeat the previous experiment with a longer insulated wire. This wire must be long enough to reach around your room.
- Ask someone to read the voltage while you move the other end of wire around the room. Do you get different readings in different parts of a room? Do you get more or less readings when you move the wire near a television? fluorescent light? electric fan? refrigerator?
Hearing noises in a copper wire
Introduction: Many electromagnetic waves like radio waves are continuous and induce a voltage in conductive material that can be measured; however, some other waves are produced only for a fraction of a second, like waves produced by switches when we turn on and off an electric device. Voltmeters do not show such voltage; but if we convert them to sound, we can hear them.
- Get two pieces of insulated copper wire, about 5 to 10 feet each.
- Remove the insulation of about one inch of each end of both wires.
- Get a set of amplified computer speakers (electric or battery operated). Turn on the speakers and set the volume at its highest possible.
- Ground one contact of the speaker. To do this, use one wire to connect one contact of the speaker to a water pipe or faucet. (Water pipe and faucet are considered ground)
- Connect the other wire to the other contact of the speaker.
- Do you here the sound produced by electromagnetic waves?
- Move this last wire close to a fluorescent light, electric motors, power adaptors, and other electrical equipment. Do you hear different noises? Do you hear any radio stations?
- Turn on and off a light bulb in your your room. Does this action send a noise into your copper wire causing a tick sound ?
The effect of wire length on the amount of noise interference
Introduction: When electromagnetic waves produced by one wire or device enters another wire or device we call it interference. Voice and data are being transmitted to very long distances; so the wires are exposed to many different interferences. Does the length of wire increase the amount of noises and electromagnetic interferences that are absorbed by wires? If this be the case, long distance transmission of voice or data will become very hard or even impossible. In this experiment, you will test the effect of wire length on the amount of noise or electromagnetic interference. Record your results in a table and then use your results table to draw a graph.
- Get about 10 pieces of insulated copper wires in different lengths.
- Remove the insulation of about one inch of one end of each wire.
- Mount the wires or simply hang them somewhere.
- Get a high precision digital voltmeter and set it to AC volts (AC stands for Alternative Current. Note that all electrical waves are alternative current).
- Connect the black/ ground electrode of the voltmeter to a water pipe or faucet.
- Connect the red electrode of the voltmeter to each of your 10 wires, where you removed the insulation.
- Record the voltage (millivolts) that you read on the voltmeter in a table like this:
Wire length Noise Voltage in mV 1′ 2′ 3′ 4′ 5′ 6′ 7′ 8′ 9′ 10′
Use the above table to draw a bar chart or line graph.
Does the amount of noise increase by the length of wire?
Materials and Equipment:
Complete list of material can be extracted from the experiment section.
- Amplified speakers (From computer stores and electronic stores)
- Digital multimeter, able to show millivolts. (From MiniScience.com, Radio shack, or other electronic stores.)
- 50 feet insulated wire (sold, single strand or twisted pair that you can easily separate). From hardware stores.
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.
No calculation is required for this project.
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 analysis of data. At this level, science becomes even more interesting and powerful.
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.
I was wondering if the plastic insulation on copper wires have any effect of reducing noise. So I repeated the experiment 1 with insulated wire and bare wire of the same type. I learned that…. (Do it yourself).
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.
Visit your local library and find some books related to radio and electromagnetic waves. Find out how in radio and television we filter the noise and get a clear sound or picture.