# Resistance in a Wire.

Essay by jonnylynchJunior High, 9th gradeA, October 2005

METHOD:

Equipment

Nichrome Wire

Ruler

Power Supply

2x Crocodile Clips

4x Wires

Ammetre

Voltmeter

Before I started the experiment, I made a trial test using a type of software called "Focus Educational Software Science Investigation. Here are the results of the experiment.

Unfortunately, the software only gave the voltage and current in two decimal places. This is why the r2 was not 1 but an extremely good 0.9991. R2 is a mathematical value given on a graph to show how reliable the data is. It gives you a reading based on the distance the points are away from the line of best fit (trend line).

I learnt that the accuracy of the reading is essential as a slight change of even 0.01Volts change have a great affect on the Resistance. Also the reading are not the same every time and does change during the experiment so in my main test I will take a reading once the Voltage or Current have settled.

To carry out my experiment I will start with a metre ruler and a piece of Nichrome wire taped at each ends. I will set up a circuit like the one below and I will put a power supply on 2 Volts so that the wire will remain cool and keep the test fair. I will range my measurements from 10cm to 100cm going up in lots of 10cm as this will give my a good indication of the resistance in a wire. I will not do it every 1cm or 5cm as the clips are 4mm wide so there will be a big margin of error in my results.

Test 1 Test 2 Test 3 AVERAGE

Length of Wire (cm) Voltage Current Resistance Voltage Current Resistance Voltage Current Resistance Resistance

0 0.00 0.00 0.00 0.00 0.00 0.00...