Voltage & Temperature
Temperature has an affect on the experiment as the voltage has control over the temperature. The more the temperature increases the more the particles vibrate leading to a reduction in output voltage although not by a huge amount this does have an affect.
Density
Density has a large affect on the amount of resistance. The resistance depends upon the amount of denseness e.g. a large surface area has less resistance because a small area has tightly packed atoms which in turn rebound many of these electrons.
Apparatus:
· Power Pack
· Constatan wire
· Leads
· Voltmeter
· Ammeter
Method:
1. Arrange apparatus as shown in the Diagram:
2. Cut wires to the following lengths:
· 3cm
· 6cm
· 9cm
· 12cm
· 15cm
3. Attach the wire to the crocodile-clip leads and set voltage to 5 volts or 1.5 Volts
4. Take the reading from the ammeter and record in results table.
5. Repeat 4 times for each length of wire and find the average.
6. Then work out the resistance using the formula V÷I=R
Preliminary Experiment
We carried out a preliminary experiment to see the other factors that could affect the experiment and also to see if we could improve any of the steps in the method. This showed that the wire was very weak if given more than 5 volts because the wire lets electricity flow faster and faster which then leads to the heat eventually breaking the wire. I found that if I decreased the voltage to a reading of 1.5 volts the wire stayed in tact enough to give a good reading and thereby giving better overall results.
Voltage used 5 Volts
Voltage used 5 Volts
Results
Conclusion
I came to a conclusion that the decrease in current is the increase in resistance this is because the current although less of it they collide with the resistance causing a decrease in the output voltage.
Evaluation
The experiment proved to be a success and it went very well although it could be improved by trying other lengths, different voltages but also a different type of wire to be able to compare the resistance difference this would make a more interesting experiment