Wouldn’t it be great if you have a handy dandy conductivity meter? That way, you can easily determine if something conducts electricity or not. It can protect you from being electrocuted. Plus, it is just a cool gadget to have.
So how can you have your own conductivity meter?
What you will need:
- Christmas lights – including wires
- Aluminum foil or stainless steel wire
- 9V battery
- Wire strippers (or scissors)
- Popsicle stick
- Salt (or other ionic solution for testing)
What you need to do:
- Cut off a Christmas light bulb and leave around 2 inches of wire from the base of the bulb. Expose the interior wires through wire stripping.
- Put tape around the top edge of the 9V battery. Insulating the metal casing of the battery will minimize the chances of a short circuit. Note which part is the positive and which is the negative terminal.
- Wrap one exposed wire of the light bulb with foil. Attach this to the positive terminal of the battery. Secure this connection with tape.
- Take the aluminum foil and roll it into two tubes. You can also use stainless steel wires. This will be used to test the conductivity of the solutions.
- Attach one of the aluminum tubes to the negative terminal of the battery and secure the connection with tape.
- Wrap the other aluminum tube around the exposed wire of the Christmas light bulb. Tape to secure.
- Test the device by putting the two aluminum tubes together. If the bulb lights up, then it works. If not, then you need to check the connections. Be careful not to connect the two tubes together for long as it might cause the bulb to burn out.
- Tape the battery in the middle of a popsicle stick. Both ends of the stick should be free so it can be used to prop the device on top of a cup with the ionic solution.
- Make sure the aluminum tubes and Christmas light bulb that are connected to the battery are both free. The aluminum tubes should be dangling from the stick so that they can be immersed in the ionic solution when the popsicle stick is propped on top of the cup.
- Take the cups of solutions and prop the stick on one of them. Dip the aluminum tube. If the bulbs light, then the solution is conductive.
What just happened:
If the solution lights up the light bulb, then it means it contains electrolytes. These are particles or ions that are charged. The ions come in both positive and negative charges. It will be attracted to the aluminum tube that is connected to the opposite of their charge. That means the positive ions will be attracted to the negative aluminum tube while the negative ions will be attracted to the positive aluminum tube. When this happens, the circuit is completed and that causes the current to make the Christmas light bulb light up.
Read more posts about experiments with batteries.