Investigating How the Length of a Wire Affects Its Resistance

Investigating How the Length of a Wire Affects Its Resistance

Planning:

Risk Assessment:

* I will handle the power supply carefully.

* I am going to only use a maximum voltage of 2 volts.

* I will be careful when handling the mains equipment.

* I will make sure I have a clear space to work in and nothing on

the floor around me.

In this investigation, I will set up a simple circuit to be able to

read the voltage and current when the length of wire changes, so I

then can work out the resistance. I will be using constantan wire

starting of with 1m length and then decreasing it by 0.10m intervals

down to 0.20m long. I will not go above 1m or below 0.20m because it

may be too long that they resist so much current that the wire burns,

or the length of the wire is so small that it doesn't resist any

current at all. The length of the wire will be changed by moving the

crocodile clip across the wire on a ruler. The independent variable

will be the length of the wire because that is what I will be

changing. The dependant variable will be the resistance because it

will change only due to the length of wire.

The circuit should be set up as in the circuit diagram below. It is

important that the voltmeter is set up in parallel and the ammeter in

series.

Battery[IMAGE]Circuit Diagram:

I will work out from the readings of the voltmeter and ammeter the

resistance in the circuit. This can be done using the formula:

R=V/I Where R= Resistance, V= voltage, I= Current.

This means I can find and record the resistance. This will work out

the resistance in ohms.

Equipment:

* Power supply

* Constantan Wire 1m

* Voltmeter

* Ammeter

* Metre ruler