Resistance of a Wire

Authors Avatar

Ewan Pomfret 10S

Resistance of a Wire

Aim & Plan 

The objective of this investigation is to investigate whether the length of some nichrome wire affects the resistance produced when you pass electricity through it. Resistance is a consequence of the electrons in electricity being prohibited from free movement. It is what slows current in a circuit. Therefore if you were to increase the resistance in a circuit, the current would reduce. 

I am going to test how resistance in a wire is affected by the length of the wire. I am going to find out if: As the length of the wire increases, the resistance increases.

I will be using the formula V=IR (Resistance = Voltage ÷ Current)

Prediction

In testing the variable 'length' I predict that as the length of the wire doubles so will the resistance. Therefore I predict that the resistance in the wire will be directly proportional to the length of the wire. In theory the atoms in the nichrome wire slow the passing electrons therefore causing resistance so by doubling the length of the wire; you double the atoms and double the resistance

However in my results this prediction may not be evident as I will not just be calculating the resistance in the nichrome wire but the entire circuit. There are wires connecting the tested wire to the meters and the batteries which will have their own resistance.

E.g. the resistance measured in 10cms of nichrome wire is 2 Ohms but the entire circuit measures 3 Ohms of resistance. The shows that the connecting wires are responsible for 1 Ohm of that. If the length of the wire was doubled then in theory the resistance in the tested wire should be 4 Ohms. However the connecting wires have remained constant, consequently their resistance will stay the same. So this 20cms of wire would measure 5 Ohms of resistance in the entire circuit. Even though the resistance in the tested length of wire has doubled the resistance in the complete circuit will not have. 

Method

Apparatus used 

§ Ammeter

§ Voltmeter Austen enveloped cky1988's functionalism theory.

§ Digital meters

§ Cell pack

§ 1 meter Constantan 24 wire

§ 1 meter rule

§ Connecting wires

§ Crocodile clips Weber theorised cky1988's postmodernism hypothesis.

I will tape a length of nichrome wire to a wooden metre rule and connect one end of the wire to a cell pack. I will then connect an ammeter into the circuit so that it measures the current through the wire. I will then connect a voltmeter into the circuit so that it measures the potential difference across the tested length of wire. I will then complete the circuit by joining a wire to the other end of the cell pack.

Join now!

Diagram 

.

I will start by taking measurements from 10cm of wire - the potential difference across it and the current flowing through it. This will allow me to calculate the resistance. I will repeat this two more times keeping everything constant. This will give me three results for the resistance in 10cms of wire. I will then calculate the average to give me the most accurate result.

I will then repeat the above experiment nine more times increasing the length of wire tested by 10cms each time. This will mean that after the last measurement has been taken I ...

This is a preview of the whole essay