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Electromagnets are a type of magnet that we can switch on and off using electricity.
But what factors affect the strength of the electromagnet?
Let's discuss an experiment we could use to find out!
All magnets, including electromagnets, attract magnetic materials like iron and steel towards them.
We can use this concept to test the strength of an electromagnet.
Paper clips are made out of steel, a magnetic material. The more paper clips a magnet can pick up, the stronger it is!
In our experiment, the independent variable will be the number of turns on the coiled wire of our electromagnet.
The dependent variable will be the number of paper clips picked up by the electromagnet.
Method
1. Create an electromagnet by connecting wires to a battery, and wrapping the wire around an iron nail.
2. Make sure the wire is wrapped around the nail five times.
3. Spread many paper clips on a clear surface, ensuring the clips are not stuck together.
4. With the electromagnet turned on, see how many paper clips can be picked up by placing the electromagnet gently on the pile of paper clips.
5. Disconnect the electromagnet, then wrap it around the nail ten times using the same length of wire.
6. Connect the electromagnet, and repeat the experiment.
7. Repeat this process with 15, 20 and 25 turns on the coil of wire.
We need to keep some control variables constant to make this a fair test.
First, we need to use the same battery or power supply each time. If we change the battery, it could affect the strength of the electromagnet, affecting our results.
Second, we need to use the same length of wire. If we change wires part way through the experiment, then it could affect the results.
What do you predict the results of the experiment will be?
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Here are some example results.
| Number of turns | Number of paper clips |
|---|---|
| 5 | 3 |
| 10 | 5 |
| 15 | 8 |
| 20 | 12 |
| 25 | 14 |
We can write a conclusion based on these results.
As the number of turns on the wire increases, the number of paper clips picked up increases. This tells us that increasing the number of turns on the wire increases the strength of the electromagnet.
Now let's try some questions!
