Finally! I’ve been wanting to do a program about magnetism with my scientists for quite a while and I finally found just the right experiment for us. But more on that later. First, let’s talk a little about magnets…
SAFETY RULES FOR MAGNETS
- Credit cards or bank cards (damaging the magnetic stripe on the back of the cards)
- Audio Cassette Tapes
- Older TV screens (LCD and plasma screens are not affected)
- Older computer monitors
- Video Cassette Tapes
Some of the world’s strongest magnets – neodymium magnets – are so strong that if your hand get between a 6″ neodymium magnet and the object it is attracted to, your hand would likely be crushed!
“THE IRON DETECTOR” & HOW IT WORKS
Interestingly enough, magnets are only attracted to iron…which also makes them the perfect “iron detectors.” If you hold a magnet up against other metals – steel, copper, etc. – you’ll see that there is no attraction.
Here’s a fun experiment for home, if you can obtain a smaller neodymium magnet. One of the main components of meteors from outer space is iron. And even though it is rare to see a large meteor hit the surface of the earth, we are constantly being showered with tiny pebble-sized (and smaller) pieces of meteors as they break up in the earth’s atmosphere. On his web site (with an accompanying video), Steve Spangler shows how you can detect and collect actual pieces of meteors from your own back yard!
Magnets are also made of two “poles” – referred to as the “North Pole” and the “South Pole.” Opposite poles are attracted to each other, and like poles repel each other. Thus, two North Poles will repel each other, but the North Pole of one magnet and the South Pole of another magnet will be drawn to each other. Have you ever wondered how a compass works? Well, part of a compass is always attracted to the magnetic pull of earth’s North Pole, and the other side of the arrow is always attracted to the magnetic pull of earth’s South Pole. You can even use a simple magnet to help with directions. Our scientists tied a string to a ring magnet (round magnet with an open center). If you let the magnet hang in the air from the end of the string, the magnet’s own North Pole will eventually face North directionally because it is being attracted to the earth’s North Pole!
As a group, we also talked about permanent magnets and temporary magnets. A permanent magnet – like the one pictured to the left, can actually make an iron-based object temporarily magnetic. For example, if you place a nail on a horseshoe magnet, and pull the nail away, you can then use the nail to pick up small iron-based objects (like paperclips).
THE WORLD’S LARGEST MAGNETS
What’s the biggest magnet in the world? The earth itself! In the video below, we learn a little more about how magnets work – and about the earth as a giant magnet:
As a group we also talked a bit about neodymium magnets and how strong the pull of some magnets can be. In the video below, we get a peek at the world’s largest magnet, currently housed in the world renowned “MagLab” in Tallahassee, Florida:
Electromagnets were a key focus for us given that our experiment of the day was also creating our own electromagnet using some simple-to-find items. Electromagnets are magnets that become active with the presence of electricity. Once the electricity stops or is interrupted, the object ceases to function like a magnet.
We used information and instructions from Science Bob as the foundation of our electromagnet experiment.
- 1 D-sized battery (other sizes can be used, but the experiment burns through the battery quickly so a larger battery will last longer)
- 1 large nail with flat head
- 1 36-inch long piece of copper insulated “bell wire” with the insulation stripped from both ends (it’s important that the wire is both insulated and copper…I bought my wire at a local Home Depot; it came as a red and white insulated piece wrapped together, but I simply unwrapped the two pieces so they could used individually)
- Paperclips (to test the electromagnet strength with)
The steps of the experiment are simple enough. Leaving about a 6-inch lead, you wrap the wire around the nail (being careful not to overlap the wire loops on the nail). Our scientists were each able to fit about 35-40 wire loops on their nails. When the wrapping was finished, there was a 6-inch length leading from both the top and the bottom of the nail. We then used duct tape to solidly tape the exposed copper end of one wire lead to the positive end of the D battery (the end with the bump). We then placed a square piece of tape on the other wire lead. Once the second lead is connected to the negative end of the battery, the electromagnet is fully functional and the exposed tip of your nail becomes the magnet (though it may take a few seconds to get fully charged). You will notice both the battery and the nail getting warm to the touch. It’s best if you loosely tape the 2nd lead to the negative side of the battery so that it is easy for you to pull it away from the battery and turn off the electromagnet (to preserve the charge in the battery as long as possible between tests).
One Step Further: How can you make the electromagnet stronger?
TIP – the key to the electromagnet’s strength is NOT the battery – it’s the wire! Try wrapping a second wire on top of the first wire around the nail, and connect both exposed ends to each end of your battery…
With the electromagnet active, our scientists tested the strength of their magnets by seeing how many large paperclips they could lift with the nail tip. Many of our scientists lifted 5 or more paperclips! We then moved to a table I set up with various objects so our scientists could test both their electromagnets and other permanent magnets on various objects to see which objects magnets were attracted to. Everyone had a lot of fun exploring just how magnets worked with a variety of objects. Check out the video below for some highlights from our program. See you in March for our next programs!