June 13, 2010
by: Tami O’Connor
When two 1-pound, 2-inch diameter, chrome steel spheres are smashed together, enough heat is generated at the point of contact to burn a hole in ordinary paper! This dramatic demonstration has been a favorite of students in every grade for as long as I have been teaching!
There are a few considerations when allowing students (especially younger ones) to conduct this activity on their own… First, the spheres are pretty heavy, so if they were either dropped on a foot or onto a nice tile floor, the result would not be good. Also, be sure that the only thing between the spheres is paper or aluminum foil. Fingers caught between the colliding spheres would not be happy. Finally, all participants should wear safety glasses, as it is not unusual for a small piece of paper to fly off after the spheres collide.
The Procedure for Smashing Steel Spheres:
Have an assistant hold the top edge of a piece of regular white paper vertically. Hold one sphere in each hand on either side of the paper. Quickly move the spheres together until they collide against the paper. If they do not burn a hole in the paper the first time, try again and move the spheres together more quickly. Examine the hole in the paper. You will see that the areas around the edges of the hole are actually singed, and you will smell the burning paper! Read the rest of this entry »
June 12, 2010
by: Martin Sagendorf
This 3D Magnetic Field demonstration is actually quite easy to do. It clearly illustrates that magnetic fields are not flat (as too frequently demonstrated in the classroom).
Demonstrating a 3D Magnetic Field
This easy-to-make construction requires only four components:
- A clear plastic bottle (about 1-3/4” in one dimension) – the one illustrated below is a 12.6 fl oz ultra concentrated Joy ® dishwashing soap bottle – Note that any bottle originally containing soap or detergent will require repeated rinses to completely remove all of its original contents.
- Six 17 mm x 3 mm Neodymium ring magnets Read the rest of this entry »
June 11, 2010
by: Michelle Bertke
Simple iron filings can be used for a variety of interesting experiments and demonstrations. Magnetism is a mysterious concept that can be difficult for students to grasp. Magnetic fields are the forces surrounding a magnet that are identified by how they interact with adjacent magnets and other metal objects. While magnetic fields are ‘invisible’ they can be observed by sprinkling iron filings on a white paper with magnets beneath.
By lightly coating the surface of the paper, the magnetic field will appear as filings align themselves with the field. Different magnets, depending on their strength and shape will create varying patterns in the iron filings. A bar magnet with a distinct north and south will show characteristic lines of a magnetic field. Circular magnets may show multiple lines indicating multiple magnet fields. The stronger neodymium magnets will cause the iron filings to pile up in spikes due to the increased strength. This demonstration can lead to a discussion about magnetic fields: What they are, Where they can be found, and How they are used in the world around us. Read the rest of this entry »
June 1, 2010
by: Martin Sagendorf
We recognize heat & cold, dry & damp, light & dark, and sound & silence. However… I find it absolutely fascinating to consider that we also live within something that we can’t see, hear, touch, or taste.
We all Know:
Our planet has a giant magnet near its core and that its field extends over the whole of the Earth’s surface. But, do we ever really think about this field that passes through soil, rocks, buildings… and us? Granted, relatively speaking this ‘field’ isn’t particularly strong. In fact, it’s a rather weak field when compared to those of a horseshoe magnet or, particularly, a modern Rare Earth magnet.
A Great Demo to show Earth’s Magnetic Field:
Read the rest of this entry »