Investigate the effect the thickness of wire has on it's resistance.

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Rosie Higgins                                19/11/01

PHYSICS COURSEWORK

PLANNING

Aim: To investigate the effect the thickness of wire has on it’s resistance.

Equipment: 

Nickel Chrome Wire cut into 10 pieces of 30cm length (Ruler, Pliers)

Two crocodile clips

Five Pieces of Wire

Power Source

Variable Resistor

Ammeter

Volt Meter

Method:

  • The Circuit was set up as in the circuit diagram overleaf with a power source of 5 Volts, an ammeter, crocodile clips (holding wires), and a variable resistor in series and a Voltmeter in parallel with the wires.
  • Nickel chrome wire was then measured to discover the cross section width with a micrometer screw gauge and this was recorded and the cross sectional areas was calculated using πr² multiplied each time by the number of wires used, each bit of wire was cut into lengths of 30 cm
  • The crocodile clips held one piece of nickel chrome wire of thickness 34 mm and length 30 cm at the same point on the ends of the wire.
  • The power source, ammeter and voltmeter were then switched on.
  • The voltage and current for the wire were then recorded, and recorded again when the variable resistor’s slider was moved to the middle and again when the slider was moved to the end.
  • The Power was turned off while another was added to avoid overheating.
  • Another wire, or exact same properties (Nickel Chrome, thickness 34 mm and length 30cm) was placed on top of the previous wire, in the same position, both straight and flat.
  • The Power was turned on again and the same procedure was repeated, recording current and voltage at three points on the variable resistor.
  • This was repeated 10 times in all, each time, an extra wire of exact same properties (Nickel Chrome, thickness 34 mm and length 30cm) was placed on top of the previous wire in the same position, all straight and flat and the current and voltage was recorded at three points on the variable resistor.
  • The resistance was then calculated using the formula R =V/I (resistance equals voltage (v) over current (a)) for each thickness of wires, three times and
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NB. When each wire was added, the power was turned off to prevent overheating.

Preliminary Experiment

A week before I did the experiment, I did a preliminary experiment in which I could investigate the conditions I could introduce to my experiment and decide upon the variables and things that should remain consistent and how I could make it a fairer test. In this experiment, I identified: the voltage, the wire type, the wire length and revised the best way to set up my experiment. I discovered that anything above 7V was very hot and caused the wire to heat ...

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