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# Does the length of a conduction putty affect its resistance?

Extracts from this document...

Introduction

Physics coursework - Does the length of a conduction putty affect its resistance?

Hypothesis:

I predict that as the length of the conducting putty increases, its resistance will increase. This is because as the length of the conducting putty increases, the current will have to pass through more molecules of the element(s) that the conducting putty is made of. This will make it harder for the current to pass through the conducting putty and so the electrons that compose the current will collide with more of the elements that make up the conducting putty. This causes friction between the electrons and the molecules and so heat is dissipated, which makes the circuit less efficient. This means that the putty is acting restricting the flow of electrons around the circuit more efficiently as its length increases, hence it is a better resistor.

In order to calculate the resistance of the wire, I plan to use Ohm's Law, the formula for this law being:

V=IR

When rearranged, it can be used to calculate the resistance of a substance, which I will need in my pre-testing and main experiment, to see if the resistance of the putty chances as its length decreases:

R= V/I

Middle

5.37

0.21

25.57

4

3.49

0.14

24.93

12

8

7.33

0.35

20.94

22.13

6

5.34

0.24

22.25

4

3.48

0.15

23.20

8

7.04

0.52

13.54

13.86

6

5.18

0.37

14.00

4

3.37

0.24

14.04

8

6.56

1.24

5.29

5.58

6

4.84

0.9

5.38

4

3.03

0.5

6.06

These results prove that the putty that I am investigating is an Ohmic conductor, as even when the potential difference changes, the resistance of the putty remains constant for the same length.

Now that I have proved that the putty does conduct electricity in a constant manner, I can start the main experiment.

Apparatus:

• 1 power pack
• 2 thin copper sheets -these are required in order to improve the efficiency of the volume of current that flows through the putty.
• Emery paper - this will be used to file the copper sheets and so improve their conductivity.
• A mass of putty
• 1 small knife

Conclusion

The other safety precaution that I will take during this experiment is to constantly make sure that there is no water near any of the apparatus that I am using in the experiment, nor nears the mains supply. I will also make sure that there is no water on my hands for the duration of the experiment, as water conducts electricity and so if I had water on my hands I could be electrocuted.

Finally, before I eat anything, I will make sure that my hands are thoroughly washed with soap and water, in order to get rid of any traces of putty that may have come into contact with my hands during the experiment, as they could be toxic. I will follow this safety precaution even though I am wearing gloves, as small tears could occur in the gloves during the course of the experiment.

Results:

On the following pages are the results that I obtained from my experiment. The 4th page of tables shows the average results that I obtained and hence used to plot the graphs that I have drawn in Analysis.

This student written piece of work is one of many that can be found in our AS and A Level Electrical & Thermal Physics section.

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