Water Drops: Cohesion and Adhesion of Water
Question & hypothesis: Will a raisin, paperclip, penny, small cork, ball of paper, and other small objects sink or float if they are placed in water, corn syrup and. To really get a sense of water's cohesiveness, scientists looked at the behavior . It is also what allowed you to float a paper clip on water and the reason why a. Sprinkling table salt in to the sky 11 miles above our planet could slow the pace of global warming, scientists have suggested (stock image).
See some of the items we chose below. Test each item by placing one gently in the fresh water measurer. So explaining salt water density to a preschooler is not the easiest task, but you can show that two things of similar size can weigh different amounts and that is what causes things to sink or float.
Things that have a higher density may sink and things with a lower density may float. Ok, so obviously we know that salt makes the water more dense allowing more types of objects float when they might not in fresh water.
Fresh water is less dense so many things sink. As the salt dissolves in the water, it adds mass more weight to the water! This makes the water more dense and thus allows more objects to float on the surface.
The best response from my son: I like to let Liam examine and observe as long as he is interested. Can you guess which one?
Salt Water Density Science Experiment
This is hard for Liam to notice on his own, but by helping him discover it by asking him questions about what he sees, he can now see it too! He can also tell you about it. You know what, it worked. Liam guessed it would sink in both and I was feeling a bit skeptical myself! I got pictures to prove it! Some I figured would be too light and some too heavy. While LEDs are a good choice for this experiment, some other ideas are given below in the section "Alternative devices".
You'll need 3 or 4. Any citrus fruit, like limes, grapefruits, or oranges, or even a potato will work. Most likely you'll use a piece of metal that's been coated with zinc. This is what the word "galvanized" means. Galvanized roofing nails, galvanized screws and bolts, and even paper clips can also work.
If you can find some zinc sheet, and some shears or tough scissors to cut it, that will work very well. Be careful if you do this; the edges of sheared metal sheets are sharp.
If you can, file the edges to make them less sharp. Copper or copper-coated pennies work well. You may find some good copper fittings in the plumbing section of a hardware store. Again, if you can find some copper sheet, and some shears or scissors to cut it, that will work. Again, be careful about sharp edges. You'll need 5 or 6. The easiest thing is to get hold of a packet of insulated lead wires with "alligator clips" on each end.
School Science/Lemon Battery - Wikibooks, open books for an open world
If you know how to use an electrical multimeter, it can be helpful in getting your battery to work. There are some little photos of these components below. If you click on the photo, you can see it larger.
LEDs light emitting diodes of different colors. The color of the plastic that surrounds each diode isn't important, and some LEDs use clear plastic.
- How Liquid Impacts a Magnet
- Exploring Our Fluid Earth
- It's Time to End the War on Salt
There's a centimeter ruler at the right that tells you the plastic cases is are about 0. Grapefruits, limes, oranges, and potatoes also work.
Zinc electrodes a collection of galvanized hardware. The flat, circular washers with holes in their center would be a good choice for a lemon cell. Copper electrodes a collection of copper pennies.
Lead wires contents of a packet of insulated lead wires with alligator clips on the ends. The multimeter in the photo is set to its 20 V scale, which means 20 volts.
For this experiment, you'd set it to read m, which means millivolts or 2. To measure the current, you rotate the center switch to the scale that reads mA, which means milliamperes or 0. Making a single lemon cell[ edit ] Make the first lemon cell. Your battery is going to have at least 3 lemon cells, but each cell is made the same way.
Clean your electrodes carefully.
School Science/Lemon Battery
Your goal is to get any dirt or grease off of them, and also to scrub away the thin "oxide" coatings on them. It should work fine if you clean them in the same way that you'd clean a pan in the kitchen to make it clean and shiny.
Scrubbing with steel wool or with an abrasive sponge will work fine; if you are using a galvanized electrode, be careful not to rub off the zinc coating completely. Stick one zinc electrode into the lemon or other fruit. You may need to use a small knife to cut a slit into the lemon.
You want the electrode to go into the lemon as deeply as possible, but you'll need a little bit of the electrode to stick out of the fruit so you can attach a lead wire to it. Wiggle the electrode around a little to smash the membranes inside the fruit.
Next, stick the copper electrode into the same lemon. You want this electrode to be close to the zinc electrode, but it must not touch the zinc inside the lemon. If they do touch, your cell will not work. As for the zinc electrode, you want to stick the copper electrode into the fruit as far as you can, and you want to wiggle it a bit to make sure the membranes near the electrode are broken.
Optional If you are using a multimeter, you can do the following tests to make sure your lemon cell is working. Hook up two alligator clips from your leads to the two electrodes. Connect the two clips to the leads of the multimeter. Measure the voltage from your lemon cell. It should read about 0. Measure the current from your cell. You should read a few tenths of a milliampere. Some multimeters are not sensitive enough to measure currents less than one milliampere, in which case you'll just see 0.
Making the lemon battery[ edit ] Three lemon cells wired together so that they energize a light emitting diode LED. Each individual lemon has a zinc electrode and a copper electrode inserted into it; the zinc is colored gray in the diagram.
When several lemon cells are wired together, the collection is called a battery. We usually call a single lemon cell a battery also. Most batteries that you may purchase to use in toys and electronics have just one cell inside. You need to make 3 lemon cells. If you're using a multimeter, make sure that each cell generates the correct voltage and the correct current.
Using two lead wires, connect the three cells together. Connect the zinc electrode on the first cell to the copper electrode on the second.