Please help me on voltage-length graphs whilst trying to calculate the resistivity of a material.
In Physics, I did an experiment on calculating the resistivity of a material by altering the length of the wire.
I have calculated the gradient of the graph, however, I am not sure of what this actually tells me? My educated guess is that it is the value of (V/L), but I'm not sure.
Could someone please enlighten me on this?
Thank you very much!
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(AQA) AS Physics Voltage-Length graphs watch
- Thread Starter
- 14-11-2015 14:04
- 15-11-2015 09:18
Im not sure about this (since I did alternative to practicals) but if we look at the formulae:
1. Resistance = (resistivity of the material X length of the wire)/ cross sectional area of the wire
2. Voltage= resistance X current (V=IR)
Since you drew a graph of Voltage against length, we need voltage on one side and length on the other
R= V/I - valid.
V= (pl X I)/A (in words, voltage = resistivity into length of the wire into the current divided by the Area)
Since y= mx + C (the gradient of a straight line)
the gradient of a Voltage-length graph should give you (pXI)/ A i.e resistivity into current divided by Area.
I hope you can understand how I got the gradient (The i and the l look very similar, sorry about that.)