What Material Makes the Best Rheostat? By Tommy Belansen

Question: Which material makes the best rheostat?

Explanation: A rheostat is a tool that controls the flow of electricity.

Hypothesis: I predict that nickel will have the best outcome because it will have the biggest difference in electricity.

Procedure:

1. I will get put several coils of wire onto a a nylon pipe.

2. I Will connect the ohm meter to a battery and start moving it along the coil of wire.

3. I will then see which coil of wire had the most change in electricity from the start of the coil to the end.

4. I will record the info then compare all of them.

5. I will test all of the metals twice to make sure that my info is correct.

Abstract:

For my Science Fair project I tested which material would make the best rheostat. A rheostat is a piece of metal that controls how fast an elevator door goes, or how bright or dim a light could be and so on. I am measuring this in ohms, the higher the ohms reading, the more resistance. Therefor, a light would be dimmer and an elevator door would go slower.The less resistance means that an elevator door would go very fast and a light bulb would shine bright. I chose to do this project because I always am mad when an elevator door closes so slowly when i'm in a rush. I have seen some elevator doors that are extremely fast, and others that are like molasses. I wanted to see what controlled them and if it was possible to change it.

All the nylon pipes were 12 inches, and in each one different wires were strung through. I had to decide whether I wanted to test every one inch or every half inch. I decided to do every half inch because I could get more accurate data from doing more tests. I had to mark down every half inch of the pipe with a sharpie marker so I could know where to place the ohmmeter prongs. For every half inch on the pipe I had to place the prongs of the ohmmeter and wait about thirty seconds for the numbers to level out. After that I marked them down and I was finished testing.

For Aluminum the first half inch read .1 ohms and the last half inch read 2.2 ohms. This didn't have much difference in resistance, therefore it would not make a good rheostat. Copper was even worse than Aluminum, the first half in had a reading of .1 ohms and the final half inch had a reading of 1.5 ohms. Copper would be the another bad rheostat because it had little to no change in resistance. Steel had a starting reading of .8 ohms and the final reading was 5.7 ohms. This had some change in resistance, but it was not the best. Last but not least, nickel. Nickel’s first reading was 4 ohms and final reading was 71.2 ohms. This would make the best rheostat out of all the materials because it had the most change in resistance. Which would make an elevator door go from as slow as a turtle to going so fast it will break.

This project made me learn that not all metals are the same. All metals are not good conductors, good magnets, or good rheostats. My hypothesis was correct, nickel did have the most change in resistance. My tests were very accurate because I waited for the numbers on the ohmmeter to level out so everything was even. Some numbers didn't level out for minutes, others gave in right away. I used the same tactics for every single test I did and double checked myself when I was the least bit unsure of anything. This project was a great success for me, before this project I was wondering many things about how things were dim and bright, or slow and fast, now I don’t wonder anymore.

Conclusion:

In these tests I found out that nickel would make the best rheostat. Therefore, my hypothesis is correct. Nickel came out to be the best because the atoms in it are very loosely packed, so it creates more resistance. Copper on the other hand is very tightly packed, so there is almost no resistance at all. I could have made the rheostats longer or shorter, the gauge of the wire could be thicker or thinner, and I could have tested the metals at different increments. My project was very accurate because I gathered a large data sample and I held the ohm meter as steady as possible and as long as I needed until the numbers were steady and accurate.