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Investigating Ohms Law.

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Introduction

Christopher Prentis 11OW                Physics Plan

Introduction: In this experiment, we will be investigating Ohms Law and we will be doing this by testing the potential difference across a wire.  The ohm law is R=I/V

Where R = resistance

I = current

V = Voltage

I predict that the factors that can affect the potential difference of the wire are:

  • Length of wire
  • Thickness of wire
  • Temperature
  • Type of material

Ohm’s Law which states “The amount of current flowing in a circuit made up of pure resistances is directly proportional to the electromotive forces impressed on the circuit and inversely proportional to the total resistance of the circuit.” It is measured in (Ω) and the equation used is:

Resistivity Ω =  Voltage V

_________

 Current A

I think the length of the wire is directly proportional to resistance.

...read more.

Middle

Apparatus: Cell                        Volt meter

              Nichrome wires                Ruler

              Crocodile clips

Safety: To make this experiment safe, I will not short circuit the battery, and also I will check the circuit before completing it.

Method:

  • Take a 2V cell and connect it to wire 1 at point A on the above diagram using crocodile clips.
  • Measure the length of wire 1 using the ruler
  • Connect wire 1 to wire 2 at point B on the above diagram using crocodile clips
  • Attach wire 2 to the cell at point C on the above diagram again using crocodile clips
  • Attach the volt meter to points B and C
  • Note the reading of the meter on the table below
  • Change the length of wire 1 and reattach the wire into the circuit
  • Note down the new length and new voltage
  • Repeat the above steps for at least 10 times, to obtain a more accurate set of results for drawing the graph
  • Draw a graph and plot the results obtained using the results table below.
...read more.

Conclusion

c6">52

0.84

50

0.81

48

0.79

46

0.76

44

0.72

42

0.71

40

0.67

38

0.62

36

0.58

Conclusion:

As you can see from above, the results I obtained prove that the prediction I gave was correct.

Graph:  See attached sheet

Evaluation:

The experiment went well, but I think that I could improve the experiment by having a more sensitive voltmeter and also by having a more powerful cell.  From the results I have acquired, I was able to produce a reliable conclusion, which supports my theory in my prediction that as the length of the wire increases, the potential difference increases, and so does the resistance.  I think my results are fairly reliable, as they are closely correlated to the line of best fit I have drawn. Also my graph proves that the results had little flaws due to the line of best fit and they also confirm my predictions.

...read more.

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