Teacher Activities

A partial listing of the teacher activities is contained here.

 What Do Magnets Attract? The Magic Dollar Bill Which Materials Does Magnetic Attraction Pass Through? The Mysterious Coins Which End Of A Compass Is the North Pole? Which Part of a Bar Magnet Attracts the Most? Identifying the Poles of a Magnet Telling Time With a Compass Floating Magnets Making a Nonmagnetic Compass

### 1-1) What Do Magnets Attract?

Material: Collection of items in plastic bag, magnet.
1. Take each item out of the bag and see whether it is attracted to the magnet. Separate the items into two piles of items that do and do not attract the magnet.
2. Go around the room and touch at least ten different items to see if they are magnetic. Do not touch any electrical outlets!

QUESTIONS/CONCLUSIONS
1. What is unique about each pile in 1)? Are there one or more characteristics that are common to each of the two piles?
2. Are all the metals attracted to the magnet? If not, which ones are and are not?
3. Of the items that are attracted to the magnet, which part of the magnet seems to attract them the most?
4. Repeat some of the tests but do not actually touch the item. For the magnetic ones, can you feel the attraction without touching?
5. Discuss in your groups whether the magnetic items in the room make sense.

### 1-2) Which Materials Does Magnetic Attraction Pass Through?

Material: several size magnets, paper clips, plastic cup, glass jar, paper, thin plywood, book, various metals, ceramic.
1. Put each of the material above between the magnet and the paper clips in turn. Move the magnet around and see if the paper clips follow.
2. Put water in the drinking glass or pie plate. Place the paper clips in the water and see if the magnets attract them?

QUESTIONS/CONCLUSIONS
1. Does the movement of the paper clips depend on the strength of the magnet? Explain.
2. Can the paper clips be moved by acting through the book? By the weak and strong magnets? Explain any difference.
3. Find out how many pages of the book each of the magnets seems to be able to attract through.
4. Does the magnet act through the metals? Does it depend on which kind of metal? How can you explain this?
5. Does the magnet act through the water?

### 1-5) Which End Of A Compass Is the North Pole?

Material: compass, bar magnet.
This activity is a good one to do with the entire class. Distribute a compass to each group. Ask them "Which end of the compass is the north end or north pole?" "How can we find out?" They should use the marked bar magnet to determine north and south. Draw two diagrams: one with the north end of the bar magnet near the compass and one with the south pole near the compass. Make sure N and S is marked on the compass. Then draw a diagram of the compass placed on earth with the north and south poles of the Earth marked.

QUESTIONS/CONCLUSIONS
1. How can you determine experimentally which end of a compass is actually north?
2. How could you find out which end of a compass is north if you don't have another magnet?
3. Hang the bar magnet from a string. Which end points in the north direction? Explain.
4. Which magnetic pole is located at the north end of the Earth?
5. Why do we call the end of the compass that points in the north direction the north pole?

### 1-6) Identifying the Poles of a Magnet

Material: compass, several shapes of magnets including bar, cylinder, disk, magnet with unmarked poles (use small bar magnets). Use as many different magnets as you can find.
The pointer of a magnet that points in the north direction is actually a north pole of a magnet. Use this fact to determine which part of all the magnets is a north and south pole. Determine a way to find north and south for the disk.

QUESTIONS/CONCLUSIONS
1. How can you reconcile the fact that the north end of the compass points towards the north pole of the earth? Don't north and south poles attract?
2. Is it obvious which parts of the cylinder is north and south? Explain.
3. Which parts of each of the magnets are north and south.

### 1-7) Floating Magnets

Material: Six (or more) small disc magnets with holes in center, plastic tube, rubber stopper with one hole to fit tube.
Place a rubber stopper on the plastic tube about two inches from the bottom (already done for you). Place the magnets with holes on the tubes. Place them in different order so that they attract and repel one another. First place the magnets so that each magnet repels its adjacent ones. Hold the tube vertically and observe. Then turn the tube horizontally and shake a little until the magnets come to equilibrium. Observe what happens. You may have to remove one or more magnets when the tube is held horizontally.

QUESTIONS/CONCLUSIONS
1. When the magnets repel one another on the vertical plastic tube, do the bottom magnets change position when new ones are added to the top? Why?
2. Why are the magnets further apart on the top?
3. What is the position of the magnets when the tube is held horizontally? Is this reasonable? Explain.
4. Where are the poles of the magnets located on the discs?

### 1-9) The Magic Dollar Bill

Material: A twenty dollar bill, a one dollar bill, strong neodymium magnet, bar magnet. (Sorry, you will have to use your own currency here!)
1. Take a one dollar bill and smooth it out. Place the bill vertical and use a finger to hold it at the very top against the edge of a table or chair. The bill should hang down freely and be able to move. Touch a neodymium magnet to the dollar bill where it is light in color. Pull the magnet away slowly and see if the dollar bill is attracted and follows.
2. Now repeat the procedure with the twenty dollar bill but bring the neodymium magnet to a place on the bill where it is dark. Try to pull the bill out with the magnet.
3. Repeat the above procedure with the bar magnet.

QUESTIONS/CONCLUSIONS
1. Explain the difference. Why is it possible to move the twenty dollar bill, but not the one dollar bill?
2. Why can the neodymium magnet attract the bill, but not the bar magnet?
3. Lay the bills down on a wooden table and by moving both magnets all around both bills, try to lift them?

### 1-10) The Mysterious Coins

Material: Several American and Canadian dimes, various magnets including neodymium.
Place both coins on the table. Try to pick up both coins with each magnet. Think about the differences. For the coins that are attracted, see how many coins can be picked up with each magnet.

QUESTIONS/CONCLUSIONS
1. Explain the difference in behavior between the American and Canadian dimes.
2. Explain the difference between using the various magnets, especially the neodymium.
3. Do you predict that the American nickel will be magnetic? Explain. Try it.

### 1-11) Which Part of a Bar Magnet Attracts the Most?

Material: bar magnet, horseshoe magnet, disc magnet, BBs, small paper clips, bowl slightly larger than bar magnet (use pie dish or plastic storage container).
1. Place a bunch of paper clips in the bowl. Place the magnet inside the bowl and pull it out while the magnet is holding lots of paper clips. Where are the paper clips most strongly attracted?
2. Repeat experiment 1) using the BBs.
3. Predict what you think will happen if you repeat experiments 1) and 2) using the horseshoe magnet and a disc magnet. Then do the experiments.

QUESTION/CONCLUSIONS
1. Where are the paper clips most strongly attracted? the BBs? Does this agree?
2. Where are the poles of a bar magnet?
3. Were you surprised by the results of using the horseshoe and disc magnets? Why?

### 2-7) Telling Time With a Compass

Material: pencil, compass.
Take a compass outside on a sunny day. Stand holding the compass facing north and align the compass needle along the N direction on the compass. Place the pencil's eraser on the compass's S with the pencil at a 450 angle to the horizontal compass. The point of the pencil will be along N. Observe where the shadow of the pencil falls on the compass. You can tell the time by letting 3 o'clock being east, 6 o'clock being south, 9 o'clock being west and 12 noon being north. The time will be standard time, not daylight savings time.

QUESTIONS/CONCLUSIONS
1. Does this technique sound like any other device you have seen?
2. Why doesn't this technique work for daylight savings time? Would it be worthwhile to design a device that would work for daylight savings time?

### 2-8) Making a Nonmagnetic Compass

Material: Sharp stake, hammer, watch, large sheet of paper.
Go outside on a sunny day and drive a stake into the ground, but with it pointing straight up. Place a large sheet of paper around the stake with the 12 hour marks on the circle drawn. Look at the current time and rotate the sheet of paper until the shadow of the stake points towards the current hour. Use standard time, not daylight savings time. North will be halfway between the shadow and the number 12.

QUESTIONS/CONCLUSIONS
1. Explain how the nonmagnetic compass and the previous activity, Telling Time With a Compass, are consistent.
2. How can this device work for 12 noon?
3. When do we have to worry about the sun not producing a shadow on our clock?