Investigating the Resistance of Wire

Investigating the resistance of a wire.

Planning

For this investigation there are a number of variables that can be chosen to change or keep the same, these are:

* Length of the wire.

* Diameter of the wire.

* Type of the wire.

* Temperature of the wire.

Scientific explanation.

All electrical conductors resist current through them to some extent. This is resistance and this affects the size of the current flow. The main dependence of resistance are:

§ It's Length.

§ It's Thickness.

§ It's Material.

My Investigation.

The variable I have chosen to change is the length of the wire; I'm going to keep the material the same as this will keep the investigation fair. I am going to increase the voltage by 1 every time I finish one full length of the wire, which is 6 readings. The diameter of the wire is also going to stay the same to ensure a fair investigation.

For our investigation we're investigating the resistance of a wire with a surge of current. We're going to connect the wire to the power source but with that we connect an ammeter and voltmeter to be accurate. We then move the crocodile clip along by 100mm every reading. We are also going to increase the voltage by 1 every time. The current will go through the voltmeter so we can have an accurate reading every time. It will then go through the wire and through the ammeter so we can have an accurate resistance reading.

What it should look like:

Safety

I'm making this investigation safe in many different ways. This includes:

* Not having the voltage too high, as the wire will get too hot.

* Don't have the power on very long for each reading as this would make the wire hot and could easily cause a burn.

* Follow normal health and safety: no water near the electricity, make sure the wires aren't broken, etc.

Prediction.

My prediction is that as the length of the wire gets shorter the resistance goes down. I think this, as there will be less wire for the current to travel through therefore less resistance.

Equipment.

Power source.

Ammeter.

Voltmeter.

Leads.

Wire.

Results

Results #1

Reading no. Length Voltage Current Resistance

1 70 2.0 0.40 5.0

2 60 2.0 0.47 4.3

3 50 2.0 0.56 3.6

4 40 2.0 0.72 2.8

5 30 2.0 0.91 2.2

6 20 2.0 1.35 1.5

7 10 2.0 2.47 0.8

Results #1

Reading no. Length Voltage Current Resistance

1 70 2.0 0.40 5.0

2 60 2.0 0.46 4.3

3 50 2.0 0.56 3.6

4 40 2.0 0.71 2.8

5 30 2.0 0.93 2.2

6 20 2.0 1.33 1.5