You will need:
Cut a length of wire (try a foot or two). Leaving a few inches of the wire loose at one end, wrap the wire around the iron nail or the screwdriver without overlapping the coils, and then leave another few inches loose at the other end. Sand an inch of coating off each end of the wire with sandpaper.
When you tape the two ends of the wire to the battery, electricity flows inside the wire and and the wires, battery, and nail will get hot. Disconnect the wires from the battery when it gets warm, and allow the battery to cool before reconnecting. Always disconnect and store the battery separately from other items when you are done with your experiment!
As the electricity flows inside the coiled wire, it induces a magnetic field in the iron core of the nail. You've now generated an electromagnet, a magnet that is turned on and off by electricity!
Things to explore:
You will need:
While free floating bubbles are spherical, soap films can take on many different shapes. It all depends on the wand.
To make your soap solution experiment with the type or concentration of the soap.
A typical mixture uses a dilution of about two tablespoons of soap per cup of water.
For the wands, experiment with pipe cleaners to create a variety of shapes. To help form shapes, you can bend the pipe cleaners around small tubes or boxes. Twist or braid a few pipe cleaners together to increase their strength when you dip them in the soap solution.
You can also experiment with bending the pipe cleaners into three-dimensional shapes.
Pipe cleaners make good bubbles because they hold a lot of liquid, but they drip a lot! You can try other materials for your bubble wands such as plastic or metal wires, canned beverage six-pack rings, yogurt lids cut into spirals and more! Explore this website for more ideas on geometrical wands.
Fill your bowl or tub with enough water to cover the biggest produce. Examine your items and compare their sizes, shapes and weights. Do some feel solid or hollow? Which ones do you think will sink or float in water?
Test your predictions by placing each item in the tub to see if it sinks or floats. Does removing a rind or peel change the buoyancy? Does ripeness affect how items sink or float? What happens when you cut the food into smaller pieces?
An Explora "Try This at Home" project
One that has a moving center of gravity. Here’s how to create one at home.
You will need two balloons and some water.
1. Pour a little bit of water into a balloon and tie the neck.
2. Squeeze and push the small water-filled balloon into the empty balloon.
3. Blow into the outside balloon and tie the neck so that the little water-filled balloon is inside the outer inflated balloon.
4. Now, toss the balloon to someone else, or throw the balloon up in the air and catch it. What happens?
(A "Try This at Home" from Explora's newsletter, Explorations)
How would you design and build a structure that can transfer a small ball between two points bridging a 6-foot gap?
There are challenges to this task: you can use less but not more of the suggested materials; the ball cannot be thrown; and once the ball is in motion, the set-up and the ball cannot be touched.
(A "Try This at Home" engineering challenge using string paper clips, move small balls from Explora's newsletter, Explorations, Spring 2009)