• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10

Identification of an unknown test wireThrough the experimental determination of it's Resistivity, p.

Extracts from this document...

Introduction

Nishit Gopal        Physics Coursework        

AS PHYSICS COURSEWORK:

“Identification of an unknown test wire

Through the experimental determination of it’s Resistivity, p”

NISHIT GOPAL

Mr Toor/ Mrs Poole

Identification of an unknown test wire through the experimental determination of it’s Resistivity, p

Introduction

The purpose of this experiment is to identify an unknown wire that has been used in the experiment.  I will determine the unknown wire by working out the resistivity value of the wire.

In order for me to work out the resistivity, I will first need to determine the following:

  • The resistance of the wire;
  • The cross-sectional area of the wire;
  • The length of the wire.

I am going to use resistivity of the wire to identify it because the resistivity value of a wire only depends on the material of the wire, the area and the length of the wire will not affect the resistivity value of the unknown wire.

Before I start the experiment I already know that as the wire gets thicker, the resistance of the wire decreases, we say that the resistance is inversely proportional to the cross-sectional area of the wire (R  1/A).  The reason for this is because as the wire gets thicker, the free electrons have more room to vibrate

...read more.

Middle

  • After recording the resistance, plot the RA/L graph, and work out the gradient, which is also equal to resistivity.
  • Match the value of resistivity of the wire with one from the data book, and hence identify the unknown wire.
Diagram
Preliminary

Length/mm

Voltage/V

Current/I

Resistance/Ω

900

0.63

0.18

3.5

800

0.60

0.22

2.73

700

0.57

0.27

2.11

600

0.56

0.29

1.93

500

0.53

0.31

1.71        

400

0.51

0.40

1.28

300

0.48

0.49

0.97

I carried out preliminary work to see how the temperature of the wire was affected at lengths between 300mm to 900mm; I kept the voltage constant at 2V.  From the results table above, we can see that the resistance at 300mm was very low, hence the wire was getting too much current through it, and because it was getting excess current the temperature increased causing the wire to burn. At 900mm the resistance was too high simply because the electrons had a longer distance to travel.  For these reason I have chosen to investigate the wire using lengths 400mm, 500mm, 600mm, 700mm and 800mm.

Diameter of wire

For this I measured the wire’s diameter with micrometer six times to get a mean (average) as this increased the precision.

Length/mm

Diameter/mm

300mm

0.39

400mm

0.39

500mm

0.39

600mm

0.38

700mm

0.39

800mm

0.39

Average diameter

0.39 (3 s.f.)

...read more.

Conclusion

  • Though I took three readings of the voltage and the current, I could improve my    average by taking about five separate readings for both the voltage and the current for each length.
  • Instead of using crocodile clips to hold the wire in place, I could use pointers, this would improve my investigation because the area that is in contact with the wire would be much smaller, and therefore allow me to measure the wire more accurately.
  • I could minimise the temperature error by allocating an interval time in between each reading this would allow the wire to cool back down to room temperature.  The temperature of the wire increases slightly every time current is passed thorough it.
  • Use a wider variety of lengths to get a more spread of findings, this would help me achieve more accurate average and a better understanding of the behaviour of resistance on the wire.
  • Repeating the same investigation, but this time I would vary the width of the wire instead of the length, this would also enhance my understanding of how the resistance is affected in different situations.

Overall my from my investigation I can say with confidence that my hypothesis was correct.  As the length of the wire increased, the resistance also increased.  This is due to the current having a longer distance to travel, passing an increased number of ions in the lattice arrangement of the wire.

...read more.

This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Electricity and Magnetism essays

  1. Marked by a teacher

    To investigate how the resistance, R, of a length of wire, l, changes with ...

    4 star(s)

    and the electrons move with a drift velocity v. Using the fact that current I is the charge passing per second. It can be shown that v = I / nAe. Using v = I / nAe, I could find the drift velocity of the wire I use in the experiment.

  2. Resistance of a Wire Investigation

    Set up a lamp at a set distance from the plant, ensuring that this distance is from the filament of the lamp to the actual pondweed, rather than the edge of the beaker. The light intensity was measured in the same way as described in the preliminary experiment, and assumed

  1. An experiment to find the resistivity of nichrome

    The law is usually expressed by the formula I = E/R, where I is the current in amperes, E is the electromotive force in volts, and R is the resistance in ohms. This enables us to work out the resistance using the current and Voltage.

  2. To investigate how the length (mm) and the cross-sectional (mm2) area of a wire ...

    This severely reduces the probability of an electron passing through the gaps between the atoms without colliding and losing electrical energy. Similarly, if you reduce the temperature, the vibrations become less, therefore giving the electrons a larger space, and more time to pass through.

  1. Resistance in a Wire Investigation

    Also I will make sure that the wire does not get hot by not measuring any less than 10cm. Also, I will always use the same thickness wire, 30SWG (standard wire gauge). However, when I am looking at the factor of thickness I will make sure that the wire does

  2. To see how the length of a wire affects its resistance. To find the ...

    In series the resistance across the components are added together: R = R1+R2. Whereas in Parallel the current divides, the larger part going through the smaller resistance and the smaller part through the larger resistance: 1/R=1/R1 + 1/R2. So the resistance is smaller because it is like a single wire

  1. Measuring the Resistivity of a Wire

    As there is electricity involved I will ensure that the experiment is set up away from any water or other aquatic conductors. I will make sure that the power supply does not exceed 3V so as not to have a dangerous current flowing through it.

  2. This coursework will show how the resistance of a wire, (depending on size of ...

    My results were as follows: Wire type Diameter(mm) Length(mm) volts amps Ohms Constantan 0.56 400 4.5 5.3 0.85 Constantan 0.43 400 5 3.45 1.45 Nichrome 0.43 400 4.8 1.9 2.52 Constantan 0.40 200 6.14 4.5 1.36 Constantan 0.40 300 5 2.4 2.08 Constantan 0.40 500 5.2 3 1.73 Constantan 0.40

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work