Big Idea Electricity and magnetism are part of a single force that has many useful applications such as conversion to heat, motion, and sound.
Guiding Questions How can we detect if an electric current is present in a circuit that has no receivers? How can an iron nail become magnetized with an electric current? How does the number of coils in a current carrying wire produce a stronger magnetic field in a simple series circuit? What use is an electromagnet known to have in our homes?
I spoke to the park ranger and reported your conclusions on hanging a bar magnet to use as a compass because both point to Earth’s magnetic pole. I told him about your investigations with parallel and series circuits and he gave me another challenge for you. He said that electricity and magnetism are somehow related. He said that with a simple series circuit with no receivers we can make an iron metal a magnet that could attract about 25 washers at the same time!!! He challenged us to investigate if this is possible and gave me some note on this to read to you. What do we have to investigate? What are we looking for in our investigation?
Think and talk about… • What did the park ranger say about electricity and magnetism? • What did he say about a simple series circuit? • How many washers did the metal item attract? • What does he want us to do?
Focus Question • Write a question in your notebook that is related to the scenario and can be investigated. • Your question should be correctly written; capital letter and ending punctuation. • Your question should not be able to be answered with a yes or no. • You do not need to have the same question as your group.
Class Focus Question How can we magnetize a metal item and pick up 25 washers, using a simple series circuit with no receivers?
Hans Christian Oersted In 1820 a Danish school teacher accidentally found a relationship between electricity and magnetism. As Oersted absent-mindedly laid the current-carrying wire of an electric circuit beside a magnetic compass, he happened to notice the compass needle turning. He continued his investigation by placing the magnetic compass directly above a wire with an electric current flowing through it in an N-S direction to observe its movement. Then he took the compass and placed it beneath the wire and observed. He noticed that an electric current flowing through a wire caused the wire to behave like a magnet. The wires when connected to a source of energy create a magnetic field. N
Can you replicate Oersted’s results? What did he accidentally discover? How did he test the compass? What new component did he add to the series? What do you think is the purpose of the switch in a circuit?
Prediction If we_________________________________________________________then it will _____________________________________________________________________ because_______________________________________________________________ Be prepared to share your thinking – you must have some reason for your thinking.
Our Group’s Data Collection Charts Draw pictures of the way your group will wind and test your predictions. Use 15 – 40 winds Remember to record your results
Open the switch • Place one end of the short wire on one of the clips of the switch and the other end to one clip of the source holder • Wrap the long wire around the rivet according to your group’s prediction. Connect one end of the long wire to the switch and the other end to the source holder clip. • Place 25 washers on one of the corner compartments of the circuit base. • You will have to show steps 1-4 to your teacher before the source is given to your group. • Place the source in place, and place the rivet over the washers • Connect the switch for 10 seconds to collect the washers. Then LIFT the washers with the rivet and place over the other empty compartment and turn the switch off. • Count the number of washers the rivet lifted and record it in your notebooks under trial I, then return them to the corner compartment again. • Repeat the steps 6-8 for the second trial.
Class Average Data Retesting Now, calculate the average or mean.
Read and discuss pages 25-32, “How Electromagnetism Stopped a War” and “Magnets and Electricity in Your Life.” Additional Resources: www.howstuffworks.com/motor.htm www.exploratorium.edu/snacks/iconmagnetism.html http://micro.magnet.fsu.edu/electromag/java
Making Meaning Conference • What does the data tell us about how a metal can be made into a magnet? • Let’s analyze the differences between the washers picked up with a rivet with 15 winds and a rivet with 20 winds. • What claim can we make about how and where the winds of wire on the rivet make the strongest electromagnet? • What claim can we make about the number of turns made around a wire and the total number of washers picked up? • What does the data tell us about the strength of a temporary magnet made with an electric current in a series circuit with one source?
Claims and Evidence I claim that… I know that…. I claim this because… I know this because….
Claims and evidence statements using the guiding questions How can we detect if an electric current is present in a circuit that has no receivers? How can an iron nail become magnetized with an electric current? How does the number of coils in a current carrying wire produce a stronger magnetic field in a simple series circuit? What use is an electromagnet known to have in our homes? Example for #1 I claim we can detect if an electric current is present in a circuit if _____________ _________________________. I know this because _______________________ _________________________________________________________________.
Conclusion My thinking has changed since I made my original prediction. I used to think ________________________________________________________, but now I know _______________________________________________________ ____________________________________________________________________. Today I learned__________________________________________ Reflection I wonder what would happen if… I’d like to know more about…