Investigating the Resistance of A Wire

Investigating the Resistance of A Wire

We are doing a test to see if certain things can change the resistance

of a wire. The variables we will change will be first of all the size

of the wire, and then change the amps using a rheostat (a variable

resistor).

We are going to use four thicknesses of the same wire; ‘constantan’

and connect them to a circuit to measure their resistance.

Prediction

I predict that the greater the diameter of the wire (SWG), the less

resistance there will be. Also I predict that the higher the ohms the

higher the resistance.

Hypothesis

I think that there will be less resistance in the thicker wires and

more in the thinner wires because there is more room for electrons to

pass through a thick wire than a thin one.

[IMAGE]

The diagram shows the front view of a thick and thin piece of wire

(and the lattice of metal ions). It clearly shows that the thick wire

is able to allow a lot more electrons through and a lot easier than

the thinner wire. I think that a faster flow of electrons (amps) will

also increase the resistance as more electrons will be trying to get

through the wire. I will find out if my prediction is correct by do

the test and then working out the resistance with ‘Ohms Law’. Ohms law

is, V= IR. For my experiment I will have to re-arrange this to get the

resistance, so it is R= V/I.

Equipment

- Power Pack (set to 5 volts)

- Circuit wires

- Crocodile clips

- Constantan wire (x4 at different SWGs)

- Ampmeter

- Voltmeter

- Rheostat (Variable resistor)

Goals

* I plan to collect evidence using my method(below)

* I plan to use 4 different wires

* I plan to get a few results and find an average.

* I plan to improve on what I find