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Investigation To Measure The Resistivity Of Graphite.

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Introduction

Investigation To Measure The Resistivity Of Graphite Aim The aim of the experiment is to find out the resistivity of graphite. The resistance which is measured in ohms of a resistor is applied with three basic elements. These are length (in meters) the cross sectional area which is measured in meters squared, and finally resistivity which is measured in ohms multiplied by meters. The experiment is aimed to measure resistivity of the graphite. To measure this you cannot just put a measuring device on the graphite and measure the resistivity. No resistivity is done by measuring three different readings that can be arranged in an equation. The four parts to this equation are :- A (Cross-sectional area) R (resistance) L (Length) ? (Resistivity). These put in an equation to find resistivity are:- ?= A R L So lets say if the length is doubled, then the resistance of the wire is doubled, then because of this the current is then halved. Because off this we assume that resistance is proportional to length. If the cross section area of the wire doubled then the resistance is halved because the current can flow more easily. ...read more.

Middle

Implementation 1. Measure the cross section of the graphite. 2. Make sure the micrometer is calibrated to zero. 3. Set up apparatus. 4. Set crocodile clips at various lengths of 1cm to 10 cm 5. Set current to either 0.1, 0.2, or 0.3 6. Record Voltage. 7. Work out resistance. 8. Record results onto a graph That's a basic run of what the experiment entails. results Current +/- 0.01 amps Length +/- 0.01 cm Voltage +/- 0.01 volt Resistance +/- 0.01 ohm 0.1 1 0.29 2.9 0.1 2 0.3 3 0.1 3 0.33 3.3 0.1 4 0.37 3.7 0.1 5 0.41 4.1 0.1 6 0.44 4.4 0.1 7 0.46 4.6 0.1 8 0.48 4.8 0.1 9 0.52 5.2 0.1 10 0.57 5.7 current length voltage resistance 0.2 1 0.41 2.05 0.2 2 0.47 2.35 0.2 3 0.55 2.75 0.2 4 0.6 3 0.2 5 0.73 3.65 0.2 6 0.82 4.1 0.2 7 0.9 4.5 0.2 8 0.98 4.9 0.2 9 1.06 5.3 0.2 10 1.17 5.85 current length voltage resistance 0.3 1 0.58 1.93 0.3 2 0.67 2.23 0.3 3 0.82 2.73 0.3 4 0.88 2.93 0.3 5 1.09 3.63 0.3 6 1.24 4.13 0.3 7 1.37 ...read more.

Conclusion

I would also use more currents as a variable. I would also try on accuracy on lower currents more because I found the position of the line to be at a slightly more obtuse angle than I expected. I would improve on my measuring of the graphite as it is relatively easy to break. As it is a fiddle getting the crocodile clips in the exact position is a challenge. I would also improve on the measuring instruments. I would use a micrometer to check the cross section out. Another improvement of my results would by to allow greater cooling times for the graphite, to make it a fair test. e.g. At 5.4instead of 6cm, or the connections that sent the current through the wire may have been held on tighter on one of the distances resulting in a stronger current and less resistance, and loser on the next resulting in a lower current and more resistance. So my experiment proves that if length is double then the resistance of the wire is doubled, Because of this the current is halved. And if the cross-sectional area is doubled then resistance is halved, as the electrons can flow more easily. 1 ...read more.

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