Dr Andrew French. October 2020. of a wire...electrodes lcm 10 15 20 25 30 35 40 45 50 55 60 65 70 75...
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Dr Andrew French. October 2020. TEACHER NOTES l R A =
Transcript of Dr Andrew French. October 2020. of a wire...electrodes lcm 10 15 20 25 30 35 40 45 50 55 60 65 70 75...
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Dr Andrew French. October 2020.
TEACHER NOTES
lR
A
=
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Equipment
Digital calliper(for measuring wirediameter)
Wooden mounting rigwith metre ruler attached
Electrodes(with electrically insulated handles)
2V DC power supply
1.00m of steelwire stretchedbetween terminalsWire terminals
Ammeter
Voltmeter
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Steel wire
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Place the wire between the jaws of the digital calliper to measure the diameter.
Don’t forget to zero the calliper (when closed) first!
I measured: ( )0.29 0.1 mmd =
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Measure the potential difference between afixed separation of wire. Using two electrodes connected to the voltmeter
Note if you use a single electrode, you need to be careful about the contact resistance of therest of the circuit. So using two electrodes is preferable.
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https://hypertextbook.com/facts/2006/UmranUgur.shtml
https://hypertextbook.com/facts/2006/UmranUgur.shtml
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Circuit schematic
Steel wire of diameter d
If we plot V vs d then we should get a straight line from the origin. From the gradient we can findthe resistivity .
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( )
2
23
7
4
1.6105 1.6105
0.29 10 1.6105
4 0.1173
9.07 10 Ωm
V kl
d k
I
V l k
−
−
=
=
= =
=
=
Which appears to be a plausible result
