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Factors Affecting the Strength of Electromagnets


Introduction: (Initial Observation)

An electromagnet is a device that becomes magnet when connected to electricity. Unlike permanent magnets, you can easily turn on or off the magnetic force in an electromagnet. The simplest form of an electromagnet is a metal rod (such as an iron nail) that you wrap some insulated wire on that. Electromagnets are used to make electric bells, speakers, microphones, electrical valves, electrical door openers, electric motors, buzzers, vibrators, magnetic cranes, televisions, magnetic storage device, tape recorders and many more.


This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “Ask Question” button on the top of this page to send me a message.

If you are new in doing science project, click on “How to Start” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.

Project advisor

Continue to read and learn how you can make an electromagnet and what factors affect the strength of an electromagnet. Your electromagnet will have a core of iron nail and a coil of magnet wire.

Information Gathering:

Find out about what you want to investigate. Read books, magazines or ask professionals who might know in order to learn about the effect or area of study. Keep track of where you got your information from.

Question/ Purpose:

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 find out if the number of wire loops on an electromagnet affects the strength of the electromagnet.

This is how you may present this purpose in the form of a question:

Does the number of wire loops on the coil affect the strength of an electromagnet?

Identify Variables:

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.

  • Independent variable is the number of wire loops used to construct the coil.
  • Dependent variable is the strength of the electromagnet
  • Constants are the wire type, wire thickness, The type and the size of the core.


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:

The electromagnet will become stronger if we increase the number of the loops of wire on the coil.

Experiment Design:

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.”

Simple Electromagnet

(Basic Electromagnetism Experiments and Project)

Experiment 1: Make a simple electromagnet
In this experiment you will make a simple electromagnet and then use a compass to identify the north and south poles of your electromagnet.


Materials for this experiment include:

  • Large Iron nail (such as 10d 3″)
  • 30 feet magnet wire 28 AWG
  • Double C Battery holder
  • Metal strip (used as key)
  • 3 screws
  • Piece of wood to install the the key


  1. Wrap one or two layers of masking tape on the nail to protect the wires from direct contact with nail. This nail will be the core of your electromagnet.
  2. Leave one foot of the magnet wire and then start to wrap the wire over the masking tape on the nail. This will be the coil of your electromagnet. Continue wrapping the wire until about one foot wire remains unwrapped. You may optionally twist the two remaining wires from near the nail to prevent the coil from getting unwind. (Count the number of turns of wire when winding. Record the number of turns of wire.)
  3. Use a piece of sand paper to scrub away the insulation from about 1 inch of the wire ends. You will notice a color change where the insulation is removed.

4. Mark 3 contact points on a wooden board and label them A, B and C. These points are 3.5 cm (1.5 inches) apart from each other. You will later insert one screw in each of the marked point.
5. Connect one wire of the coil to the red wire of the battery holder. (You can twist the wire ends to each other and then secure it by wrapping a tape over that. Another way to secure this connection is placing it under the cap of a screw you insert in a wooden board. That connection is marked as C in the above diagram.)
6. Connect the other wire of the coil to a screw B you insert on a board. This screw is also the contact for your key/ switch.
7. Pass a screw through the hole of small metal strip and then insert it in the position A in a way that the other end of metal strip stays over the screw B, but not touching it.
8. Connect the black wire of the battery holder to the screw A.
9. Insert the batteries in the battery holder. Your electromagnet is ready now.

Note: The diagram above shows the electromagnet nail is very close to the key and battery. Since you leave one foot wire from each end of the coil wire, your actual electromagnet will be about one foot away from the key and the battery holder. This distance is especially important for other experiments you will perform with your electromagnet.

Test your electromagnet:

Place a compass near the electromagnet and push the button over the screw B. Does the compass needle move? If it does not, there is a problem. Check all the contacts and try again. If it moves, you can continue with other experiments.

Experiment 2: Strength of electromagnet, Effect of coil loops

Introduction: Measuring the strength of an electromagnet help us determine if an electromagnet is strong enough for our specific need. It can also help us to identify factors affecting the strength of an electromagnet. By knowing such factors we can estimate the strength of an electromagnet before making it. This is especially important for large electromagnets that cost thousands of dollars.


  1. Make an electromagnet as you did in the previous experiment. use 500 turns of magnet wire on the coil. (You may want to use the same electromagnet you used in the previous experiments.
  2. Attach a small plastic cup or any similar object to a nail using threads. Make holes on the cup and use tape if needed. This will be the initial weight and a platform for additional weight.
  3. Hold the electromagnet you made in the previous experiment so that the cap of the screw will face down.
  4. Push the off/on button so that the weight platform can hang to the electromagnet using the magnetic force.
  5. Start adding some weights to the platform. Continue that until the weight platform falls.
  6. Record the total weight of the weight platform before adding the last weight.
  7. Unwind 100 turns of the coil wire and try the weight test again.

Variations: Instead of unwinding 100 turns of wire from your electromagnet in each step of the experiment, you can make 5 similar electromagnets (5 nails) and use 100 turns of wire for the first one, 200 loops of wire for the second one, 300 loops of wire for the third one, 400 turns of wire for the fourth one and finally 500 loops of wire for the fifth one. In this way you will use 4 more nails and some more wire; however, you will have chance to repeat your experiments and measurements as many times as you like.

Materials and Equipment:

Materials you need for this project include:

  • 2 Large iron nails
  • Insulated copper wire (or magnet wire) gage 23 to 28
  • Battery holder for 1 or 2 batteries
  • Some weights (or objects with known weights)
  • A simple switch
  • Other household materials as required by your experiments.

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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.

Record your data/ results in a table like this:

Loops of Wire Max Load/ weight supported


No calculations are 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.

Make a Graph:

You may create a bar graph to visually present your results. Make a bar graph with 5 vertical bars. Each bar will represent certain number of loops of wire used in the electromagnet. Name the bars 100, 200, 300, 400 and 500. The height of each bar will show the maximum load carried by your electromagnet with that number of wire loops.


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.

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.


List your references in this part of your report.