Investigation: How the Resistance in a Circuit Varies with the Length, Thickness and Type of Wire

Only available on StudyMode
  • Download(s) : 345
  • Published : April 28, 2011
Open Document
Text Preview
Investigation: how the resistance in a circuit varies with the length, thickness and type of wire

Introduction
A current is a flow of negative electrons around a circuit or electrical pathway. This is measured in how many electrons per second or the charge they are carrying go round the circuit (amps or amperes) Voltage or Potential Difference measures how much energy individual electrons have to use up as they go around a circuit. (Volts) Components in a circuit have a Resistance value which will affect the current. A mathematician named Ohm made observations which led him to formulate the law;

V =i x R
Voltage = current x resistance
(If the components are at a constant temperature)

Wire thickness is measured using swg “standard wire gauge” which is the length from a lump of metal that a wire is pulled out from. Therefore a wire with a 26 swg is thicker than a wire with 32 swg. I am going to investigate how the different lengths, gauges and types of wire can affect the current in a circuit.

Method
I am going to construct a circuit using different 100cm length wires, a battery, a voltmeter, an ammeter and crocodile clip connections. The ammeter will be fitted in series and the voltmeter will be fitted in parallel with the wire. I will use a meter ruler to measure the length of the wires each time I change the resistance by making the wire shorter by moving the crocodile clips down the length every 10cm each time starting with 100 cm. Once I know what voltage that supply is set on I will measure current in the circuit and voltage across the ends of the wire each time I change the length of the wire and from this I can work out the resistance of the wire for each length. I am going to use a 26 swg Nichrome wire, a 28 swg Nichrome wire, a 32 swg Nichrome wire and a 32 swg Constantan wire all the same length. I took a first set of readings Once I have recorded the current, voltage and repeated them. I calculated the average values. Once I have...
tracking img