Electromagnet Challenge
Subject: Physics
Grade Level(s): Grade 4
Big Idea(s): How does an electromagnet work? Can the strength of an electromagnet be controlled?
What you need: Core material; 1/4 to 1/2 inch in diameter, wood, steel, plastic, and aluminum. A variety of wire. copper, steel, aluminum, of various small gauges both insulated and non. D-Cells, evenly charged. You will also need simple switches, D-Cell holders, and 50 to 100 steel washers per group.
Setting: A regular classroom setting with the students arranged in table groups works great. It is best to have a material table manned by classroom help for the distribution of the material.
Time Needed: Depending how your science kit is organized the set up may take as little as twenty minutes or as much as one hour. The construction and testing of the electromagnets will take at least one hour. The presenting and class discussion of the team findings may take an additional hour. These sessions don’t need to be all in one go or even back-to-back.
Summary:
In this activity students will design and construct electromagnets. Each group will study one variable of the magnet to adjust while trying to increase the strength of the magnet. Depending on the number of groups some groups will be studying the same vairiable. The variables to study are number of batteries, type of wire, style of wrapping the wire, number of wraps, and type of core material. As a control each group must only adjust the one variable they are studying. The team that is investigating the core material must always use the same type of wire, the same number of batteries and the same stile and number of wraps. It is best to tell the groups that are not studying the style of wraps to wrap the core 20 times near the head or lifting point of the magnet. The team that is exploring the style of wraps can wrap neet, messy, overlapping or nonoverlapping. As the groups explore their magnets they will record their findings on a simple ‘T’ -chart to be presented to the class later. Above their T-chart they list their variable and all of their constents. The final charts are displayed on the wall for futther electromagnet activities.
Learning Goals / Objectives:
The students will: Construct and interpret graphs from measurements; Formulate and justify predictions based on knowledge gained from previous lessons; Demonstrate a knowledge of electrical currents and simple circuits; Demonstrate a knowledge that electromagnets are used is every day devices like doorbells, earphones, and generators; and Explore the scientific method by designing and implementing an experiment that uses variables and constants.
Background
Electrical motors actually run on magnetic energy, as well as electricity. A battery changes chemical energy into electrical energy. In turn, that electrical energy can produce a magnetic field. A coil of copper wrapped around a conducting rod and connected to the battery terminals creates a magnetic field inside the coil. It will make a temporary magnet out of the conductive core. Unlike permanent magnets temporary magnets may be switched on and off. The strength of an electromagnet may be controlled and effected by the way it is constructed. A few of the many uses of electromagnets are door bells, motors and MRI machines.
Setup:
Have all the materials neatly arranged on the distrubution table. Have the variable sets ready to go for the individual teams. Have the constant sets prepared aslo.
Anticipatory Set:
Show a short video clip of a large electromagnet in action. Lifting junk cars and dropping them into a crusher is perfect. Have a class discussion on other uses of electromagnets. Some common ones are doorbells, speakers, earphones, and MRI machines. “Last week (yesterday or whatever) we learned how to construct temporary or electromagnets. As we saw in the video electromagnets can be very powerful. How do you think we can make our electromagnets stronger?” Hold a class discussion and tell them that today we will be designing and performing experiments in order to develop the strongest electromagnet possible.
Instructions / Activities:
1. Step 1 Info. After the set. Have a class discussion of the variables to be tested. Review variables and constants in scientific experiments. Remind the students about the importance of the constants. Have each team discuss the variable they want to study. Help to guide the individual team discissions so every varable is covered.
2. Step 2 Info. Have the teams draw up plans for their electromagnet challenge experiment. Have them also start the presentation chart by listing the variable and the details of all the constants. After you review their plans have them write up a shopping list. The Go-For may then come to the material table for their items. If a team needs additional material the Go-For must bring a not to the person at the material table.
3. Teams now construct and perform their experiment. Circulate around the room and make sure that each team is only tweaking one variable. Every time they change the variable they test the magnet by picking up small steel washers and recording their findings on a t-chart. Remind the class that electromagnets are heavy electricity users and to always turn off their magnets when they are not lifting washers.
4. Test and record resutls.
5. Prestnt and post findings.
Assessment:
Formative assessments include;
Class discussions;
Team and individual interviews during the science activities.
Have the makings for an electromagnet and have individuals construct an electromagnet
Ask students to design the strongest magnet possible with drawings or writing.
Collect and review student science journals
Summative assessments include.
Written tests
Multiple choice questions
Vocabulary tests
Drawing an electromagnet and labeling all the parts
Wrap-up / Closure:
Ask students to design the strongest magnet possible with drawings or writing. Have all the team results posted and refer to them in a final class discussion. Now have each group, using their and others findings, design and diagram the strongest electromagnet they can with the materials at hand. They need not be construction this magnet just diagramming and discussing it. The next challenge will be to design an electromagnet that lifts a certain amount of washers. No more and no less.
