The Daring Book for Girls - Andrea J. Buchanan [34]
4. Three electrician’s clips.
5. Two lemons, or one very large lemon cut in half.
WHAT YOU DO
In five simple steps, here is how you run a digital clock on a lemon.
Step One: Place the lemons on a plate, or any flat surface that can serve as the base for the clock. Push one nail into each lemon and then, as far away from the nails as possible, also push in a strand of copper wire. Label your lemons one and two. What you’re going to do now is create a closed circuit, so energy can flow from the lemon into the clock and back again.
Step Two: Open up the clock’s battery compartment. Depending on your clock, there are two AA batteries, or a single battery that looks like a button. Remove the battery (you’ll be replacing its energy, believe it or not, with the lemon-nail-and-copper concoction you’ve just created). Notice that the positive and negative points are marked as such.
Step Three: On lemon number one, use the electrician’s clip to connect the copper wire to the positive point in the clock. This may be a challenge; in some cases it is easier said than done.
If you can’t connect your wire to the positive point in the battery compartment, you’ll need to remove the clock’s plastic backing and open up the clock. An adult should help with this, and remember, once you take the clock apart it may not go back together. Inside, you’ll see that the positive and negative points are connected to wires on the inside of the clock. You can remove the wires from the back of the battery compartment, and then use them to make your connections. If you have a two-AA-battery clock, and inside you find two positive wires, make sure you connect your copper wire with both. Once you’ve figured this out, the rest is a breeze.
Step Four: On lemon number two, connect the nail to the clock’s negative point. You may need to move the lemon into a new position so you can clip the nail to the clock.
Step Five: Link the copper wire from lemon number two to the nail sticking out of lemon number one. You’ll see now that you’ve made an entire electrical circuit, from clock, to lemon, to the next lemon, and back to the clock. If all has gone well, the clock now works, because just under one volt of electricity is coursing the circuit.
If the clock does not work, make sure all connections are secure, and then double-check the directions. If several months from now the clock stops, replace the lemons, or the nails, and it should begin ticking once again.
WHY IT WORKS
1. The nail has been galvanized, which means it was coated with zinc to help resist rust. The lemon contains acid. This acid dissolves the zinc on the nail. In chemistry terms, this means that the zinc loses an electron and becomes a positive force. (If you haven’t already read the chapter about the Periodic Table of the Elements, now’s a good time to do so.) The moisture in the lemon functions as an electrolyte, a fluid that conducts electrons—if you will, a swimming pool for electrons.
2. The electron shoots out of the zinc, through the lemon, to react with the copper on the wire. The copper gains an electron and becomes a negative force. The exchange of electrons is a chemical reaction. It creates chemical energy, or charge. All that charge needs is a circuit.
3. The electron exchange buzzes around the circuit you built—zinc/nail to copper wire to clock to copper wire to nail to lemon to copper to zinc/nail to lemon, and so on. That’s the transfer from chemical energy to electricity, and it gets the clock going as well as any manufactured battery.
Snowballs
SNOWBALLS MAY NOT BE ALLOWED in schoolyards, but this shouldn’t stop you from holding a neighborhood snowball fight when school gets canceled because of a big storm. When a snowball fight breaks out, everyone must agree to some ground rules, such as no ice, and all snowballs must always be aimed well below the neck.
There are four basic kinds of snow.
Powder. Likely to be seen on very cold days. It has low moisture content and lots of air.