Introduction: (Initial Observation)
You may use a simple electric circuit to test different materials for conductivity.
A simple electric circuit is a circuit made of a battery, a resistor and a switch connected to each other by wire in series. A resistor is any device (such as light-bulb or an electric motor) that consumes electricity. A Simple Electric Circuit is a complete loop in which the flow of electrons (or electricity) from the battery travel trough the wire and pass trough the switch, the resistor and return back to the battery from its other end.
In this project you will make and demonstrate a simple electric circuit. You will learn about electrical conductors (such as wires and metals), insulators (such as plastic coating on the wire) and the concept of electrical circuits.
Combine the joy and excitement of making educational toys with your science project by constructing a simple electric circuit you may use as a night light. This is a good way of learning about simple electric circuits.
Find out about Simple Electric Circuits. Read books, magazines or ask professionals who might know in order to learn about the role or function of each element in your circuit. Keep track of where you got your information from.
Following are samples of information you may gather:
- circuit a closed loop of conductors through which charges (flow of electrons) can flow
- conductor a substance through which electrical charges can easily flow
- current a flow of electrical charges
- generator a device for producing electrical current by moving a coil of wire in a magnetic field
- insulator a material through which electric charges cannot move
- ion an atom that has gained or lost one or more electrons and is thus a charged particle
- switch a device that closes or opens a circuit, thereby allowing or preventing current flow
- voltage the pressure behind the flow of electrons in a circuit
- electron one negative electrical charge. Electrons exist in all materials, but can only flow freely in metals.
WHAT IS ELECTRIC CURRENT?
An electric current is a flow of microscopic particles called ELECTRONS flowing through wires and electronic components.
It can be likened to the flow of water through pipes and radiators, etc.
As water is pushed through pipes by a pump, electric current is pushed through wires by a battery.
Hot water does work by heating radiators.
Electric current does work by heating fires, lighting lamps, ringing bells, electroplating, etc.
A basic law of the universe is that like charges repel and unlike attract. Two negatives will repel each other. A negative and a positive will attract each other.
An electron has a negative charge.
The negative (-) terminal of a battery will push negative electrons along a wire.
The positive (+) terminal of a battery will attract negative electrons along a wire.
Electric current will therefore flow from the – terminal of a battery, through the lamp, to the positive terminal.
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 construct, test and demonstrate a simple electrical circuit.
If you need to do an experimental project, then use this question:
Identify conductors and insulators around you. It is important to know what materials are conductive and what materials are not.
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.
This is a sample on how you may define the variables.
- The independent variable is the type of material.
- The dependent variable is the conductivity (Conductive or Insulator).
- Constants are the voltage, circuit and the test method.
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.
This is a sample hypothesis for your question:
All metals are conductive and all non-metals are insulators.
Note that the results of your experiments may show that your hypothesis have been wrong.
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.”
First Make a Simple Electric Circuit
A Simple Electric Circuit is a circuit including a power source (battery), a resistor (light bulb) and a switch connected to each other in series (meaning that wires connect the battery to the switch, the switch to the light bulb and the light bulb back to the other end of the battery).
Connection of wires to the battery holder, switch and the lamp base are usually done using the screws or clips. You can use household tools such as a pair of scissors to cut the wire and remove the insulation from the contact points. You will also need a D size battery to power your circuit.
Use the picture bellow to see how you must mount the components on the board. Use small mounting screws to mount the battery holder, the switch and the lamp holder to the appropriate places on the board. A screw driver and assistance of an expert adult may be required.
Loosen the contact screws (not mounting screws) on the lamp holder and on the switch to make them ready for connecting the wires.
Cut 3 pieces of wire (any color) to 7″, 5″ and 4″.
Remove the insulation from 1/2 inch of each end of the wires. To do that first make a cut on the plastic insulation all around the wire. Then pull the insulation out.
Use the 7″ ling wire to connect the battery holder to the one of the contact screws on the lamp holder.
Use the 5″ long wire to connect the remaining contact screw of the lamp holder to one of the screws on the switch
Use the 4″ long wire to connect the remaining screw on the switch to the remaining clip of the battery holder.
These pictures on the right show how you connect and secure the wire to the battery holder clips. Simply push the spring, insert the wire and then release the spring. (Handle the clips with care because they may come off with excess force)
To connect the wires to the screws on the lamp holder or the switch, first bend the end of the wire like U shape and then hook them under the screw, and then tighten the screw.
1. No electrical contact will be made if you have not removed the insulation from the ends of the wire.
2. Do not use flame to remove the insulation. Doing this is dangerous and will blacken the ends of the wire.
Test your circuit:
Insert the battery, screw a light bulb into the lamp holder and close the switch. The light bulb must light up. If it does not check all the contacts and try again. You may also need to check the battery and the light bulb.
Experiment: Identify conductors and insulators around you. or
What Materials are Conductors of Electricity?
Introduction: By learning about conductors and insulators we can keep ourselves and our electrical equipment safe. Every year thousands of children and adults around the world are electrocuted because they did not use proper insulation while contacting with electrical wires or equipment. So much loss of life is a clear signal that every one must learn about electricity and safeguarding it by using insulators. This experiment is a fundamental step toward such education.
Procedure: Make sure the switch in your simple electric circuit is open and the light is off. Then place different objects between the poles of the switch one at a time. If placing the object between the poles of the switch can close the circuit and the light bulbs turns on, then the object is conductive. If the light does not come on, then the object is an insulator. Some of the objects you may try are: Coins, nails, gold and silver pieces, paper clips, safety pins, Pencil and the pencil’s lead, rubber, wood, plastics, glass and aluminum foil.
Your results table may look like this:
|Coin (US Quarter)|
Warning: The voltage (electrical power) of a battery (also known as dry cell) is usually about 1.5 Volts. When a material is insulator for 1.5 volt, it may be conductive for higher voltages. Even air is conductive for high voltages. You must be more careful as you start experimenting with higher voltages in future.
Materials and Equipment:
The materials you need for making a simple electric circuit are shown bellow.
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 calculations are required for this project; however, if you do any calculations, make sure to write them in this section of your report.
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.
Why don’t the birds get killed when they sit on high voltage electrical cables?
This is a common question for those who know “most high voltage electrical cables have no insulation.”. The answer is simple. High voltage electricity can kill if it passes trough your body. When birds sit on the power cable, the electrical current cannot pass trough their body because no part of their body is touching the ground or any other wire. With the same token, someone wearing thick rubber shoes may touch a 110 volt electrical cable with one hand and stay safe; however, the same person may get electrocuted if he is touching a moist concrete wall or a water pipe with his other hand. For very high voltages such as 6000 volts, no insulation can protect us and we must stay at least 5 feet away from such high voltage cables. (That is why such cables don’t have any insulation on them).
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.
List your references in this part of your report.