Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area...
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Transcript of Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area...
![Page 1: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/1.jpg)
Making your own Resistor
![Page 2: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/2.jpg)
Shade an area on grid paper 1cm x 20cm
Make sure that you shade this area really, really well! It must be really shiny otherwise the resistor will not work!!
![Page 3: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/3.jpg)
Now get an orange multimeter. Connect two wires to the bottom two sockets:
![Page 4: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/4.jpg)
Set the dial of the multimeter to Resistance (this symbol: Ω) and to the setting that says 200k
![Page 5: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/5.jpg)
Using the multimeter, measure the resistance of the shaded area 1 cm at a time. Record the resistance each time.
![Page 6: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/6.jpg)
Using the multimeter, measure the resistance of the shaded area 1 cm at a time. Record the resistance each time.
![Page 7: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/7.jpg)
Using the multimeter, measure the resistance of the shaded area 1 cm at a time. Record the resistance each time.
![Page 8: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/8.jpg)
Using the multimeter, measure the resistance of the shaded area 1 cm at a time. Record the resistance each time.
![Page 9: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/9.jpg)
Using the multimeter, measure the resistance of the shaded area 1 cm at a time. Record the resistance each time.
![Page 10: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/10.jpg)
Using the multimeter, measure the resistance of the shaded area 1 cm at a time. Record the resistance each time.
Make sure that the wires are pressed firmly down on the shaded area. If you don’t get a reading, shade the area again some more!
![Page 11: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/11.jpg)
Measure the resistance from lengths of 1cm to 20cm and record your data on the following table:
Length / m
Resistance / Kilo Ohms
Plot a scatter graph of your results. Put length on the x axis (horizontal) and resistance on the y axis (vertical)
Do not join all the points up, instead draw a line of best fit!
![Page 12: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/12.jpg)
Your graph should look something like this…
Resistance / Kilo ohms
Length / cm
x
x
x
x
![Page 13: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/13.jpg)
Conclusion
• How did the resistance of the shaded area change as you changed the length?
• Why do you think this happened?• What do you think would happen to the
resistance if you made the shaded area even more shiny? Why?
![Page 14: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/14.jpg)
Resistance
• R is proportional to the length of wireR α L
• R is inversely proportional to the cross sectional area of wire
R α 1/A
• R depends on the type of material – WHY?
![Page 15: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/15.jpg)
Resistivity
R = ρL A
where R = resistance in OhmsL = Length of conductor in metresA = cross sectional area of conductor in m2
ρ = resistivity of the material in Ohms.meters
![Page 16: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/16.jpg)
Example
The resistivity of copper is 1.7 x 10-8 Ωm. What is the resistance of a piece of copper wire 1 m in length with a diameter of 0.1mm?
![Page 17: Making your own Resistor. Shade an area on grid paper 1cm x 20cm Make sure that you shade this area really, really well! It must be really shiny otherwise.](https://reader035.fdocuments.net/reader035/viewer/2022070401/56649f215503460f94c39781/html5/thumbnails/17.jpg)
Example
The resistivity of copper is 1.7 x 10-8 Ωm. What is the resistance of a piece of copper wire 1 m in length with a diameter of 0.1mm?
radius = 0.05mm = 5 x 10-5mcross sectional area = πr2 = 3.14x(5 x 10-5)2 = 7 x 10-9 m2
R = ρL/A = (1.7 x 10-8 x 1)/ 7 x 10-9 = 2.42 Ω