How Does the Length of Wire affect Resistance in a Circuit? Physics Higher GCSE Coursework - page 1
Keywords: How Does the Length of Wire affect Resistance in a Circuit? Physics Higher GCSE Coursework, A*, electricity, double award, triple award
By Glamurus on 02/11/2006
Level: GCSE Key Stage 4 (Years 10-11)
Page Number: 1 of 3 pages: 1 2 3
How Does the Length of a Wire Affect Resistance?
Introduction
I am going to investigate how changing the length of a wire within an electrical circuit affects the resistance in the circuit.
Resistance is anything in the circuit which slows the electrical current down. Resistance opposes the current flow. It’s measured in ohms (Ω). The equation to find resistance in a circuit is as shown:
Resistance = Potential Difference/Volts (V)
Current/Amps (A)
Variables
The input variables that I could change in this experiment are:
• Length of wire
• Width of wire
• Temperature of the environment the circuit is in
• Material wire is made of
• Size of power source
I have chosen to vary the length of wire.
Prediction
I predict that the longer the wire, the greater the resistance. This is because if the wire is longer, the current will have a greater distance to travel, and give more time and space for the ions to travel against the current and create resistance.
List of Apparatus
1 Ammeter
1 Voltmeter
5 Wires
1 Length of Wire (1 metre)
2 Crocodile Clips
1 Cell (1.5 Volts)
1 Metre Ruler
Preliminary Experiment
I need to complete a preliminary experiment because this will identify any problems with the experiment, and I can rectify these things before doing the main experiment. It will also give me an idea of what results to expect.
Results
Length of Wire (cm) Voltage (Volts) Current (Amps) Resistance(Ω)
100 1.6* 0.06 26.67
80 1.5 0.08 18.75
60 1.5 0.1 15
40 1.4 0.16 8.75
20 1.4 0.25 5.6
* - This result is erroneous because my power source only went up to 1.5 volts. The most likely for this reading is incorrect reading of the voltmeter.
Ammendments
In the preliminary experiment, the circuit functioned, the material the wire used to vary resistance was made of was effective material and the time taken to modify the experiment to take a reading using a different length of wire was efficient. The ammeter and voltmeter also gave clear results that seem reasonable if matched with scientific law and minimal scientific understanding; the only exception to this was the anomalous result (1.6v at wire length of 100cm, which exceeded the cell’s power supply) that was probably caused by the voltmeter showing an inaccurate result. This should be solved by more accurate digital ammeters and voltmeters (see below).
I will change the cell
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