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: The greater the [[Electrical Resistance|resistance]] of a [[resistor]] the smaller the [[Electrical Current|current]] will be.
: The [[Electrical Resistance|resistance]] of a [[resistor]] can be found by attaching an [[ammeter]] in [[Series Circuit|series]] with the [[resistor]] and a [[voltmeter]] in [[Parallel Circuit|parallel]] with the [[resistor]].
: All [[electrical componentComponent|component]]s in a [[circuit]] act as [[resistor]]s, including [[wire]]s. The longer a [[wire]] the more [[Electrical Resistance|resistance]] it will have to a [[Electrical Current|current]].
{| class="wikitable"
: The greater the [[Electrical Resistance|resistance]] of a [[resistor]] the smaller the [[Electrical Current|current]] will be.
: The [[Electrical Resistance|resistance]] of a [[resistor]] can be found by attaching an [[ammeter]] in [[Series Circuit|series]] with the [[resistor]] and a [[voltmeter]] in [[Parallel Circuit|parallel]] with the [[resistor]].
: All [[electrical componentComponent|component]]s in a [[circuit]] act as [[resistor]]s, including [[wire]]s. The longer a [[wire]] the more [[Electrical Resistance|resistance]] it will have to a [[Electrical Current|current]].
===Resistors in Series===
: Adding [[resistor]]s in [[Series Circuit|series]] increases the [[Electrical Resistance|resistance]] in the [[circuit]].
: The [[Electrical Resistance|resistance]] of each [[resistor]] can be added together.
{| class="wikitable"
|-
5Ω.
|-
|[[File:ResistorsSeries1ResistorsSeries2.png|center|400px]]
| style="height:20px; width:175px; text-align:center;" |The [[Electrical Resistance|resistance]] between points A and B is:
2Ω + 5Ω = 7Ω
|-
|[[File:ResistorsSeries1ResistorsSeries3.png|center|400px]]
| style="height:20px; width:175px; text-align:center;" |The [[Electrical Resistance|resistance]] between points A and B is:
===Resistors in Parallel===
''NB: You only need to know what happens with identical [[resistorsresistor]]s in [[Parallel Circuit|parallel]].'' : When identical [[resistor]]s are added in [[Parallel Circuit|parallel]] there are more paths for the [[electricity]] so the [[Electrical Resistance|resistance]] is reduced. {| class="wikitable"|-|[[File:ResistorsParallel2.png|center|200px]]|[[File:ResistorsParallel3.png|center|200px]]|[[File:ResistorsParallel4.png|center|200px]] |-| style="height:20px; width:200px; text-align:center;" |Two identical [[resistor]]s in [[Parallel Circuit|parallel]] gives twice the number of paths, so has half the [[Electrical Resistance|resistance]]. The [[Electrical Resistance|resistance]] between points A and B is 12Ω.| style="height:20px; width:200px; text-align:center;" |Three identical [[resistor]]s in [[Parallel Circuit|parallel]] gives three times the number of paths, so has a third of the [[Electrical Resistance|resistance]]. The [[Electrical Resistance|resistance]] between points A and B is 8Ω.| style="height:20px; width:200px; text-align:center;" |Four identical [[resistor]]s in [[Parallel Circuit|parallel]] gives four times the number of paths, so has a quarter of the [[Electrical Resistance|resistance]]. The [[Electrical Resistance|resistance]] between points A and B is 6Ω.|} ===IV Graph==={| class="wikitable"|-|[[File:IVGraphResistor.png|center|400px]]|}====Description====The [[IV Graph]] for a [[resistor]] shows that:*As [[Potential Difference|potential difference]] increases, [[Electrical Current|increases]].*The relationship between [[Potential Difference|potential difference]] and [[Electrical Current|current]] is [[linear]] (the [[gradient]] is constant).*The [[Electrical Current|current]] is [[Directly Proportional|directly proportional]] to [[Potential Difference|potential difference]]. ====Explanation====: [[Resistor]]s obey [[Ohm's Law]] so the "[[Electrical Current|current]] through a [[Electrical Resistor|resistor]] at constant [[temperature]] is [[Directly Proportional|directly proportional]] to the [[Potential Difference|potential difference]] across the [[resistor]]." ====Obtaining the IV Graph===={| class="wikitable"|-|[[File:ResistorIVGraphCircuit.png|center|300px]]| style="height:20px; width:300px; text-align:left;" |#Connect an [[ammeter]] in [[Series Circuit|series]] with the [[resistor]] to measure [[Electrical Current|current]] through the [[resistor]].#Connect a [[voltmeter]] in [[Parallel Circuit|parallel]]with the [[resistor]] to measure the [[Potential Difference|potential difference]] across it.#Use a [[Variable Resistor|variable resistor]] in [[Series Circuit|series]] with the [[resistor]] to vary the [[Potential Difference|potential difference]] across the [[resistor]].#Start with a [[Potential Difference|potential difference]] of zero and increase the [[Potential Difference|potential difference]] by an interval of 0.2V up to 2V.#Recording the reading on the [[voltmeter]] and [[ammeter]].#Reverse the connections on the [[battery]] and repeat steps 4 and 5 to find the I-V relationship for negative [[Potential Difference|potential difference]] and [[Electrical Current|current]].|} ===References=======AQA==== :[https://www.amazon.co.uk/gp/product/0008158770/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158770&linkCode=as2&tag=nrjc-21&linkId=ec31595e720e1529e49876c3866fff6e ''Resistor, pages 46-7, 52, GCSE Physics; Student Book, Collins, AQA '']:[https://www.amazon.co.uk/gp/product/0008158770/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158770&linkCode=as2&tag=nrjc-21&linkId=ec31595e720e1529e49876c3866fff6e ''Resistor; non-ohmic, page 59, GCSE Physics; Student Book, Collins, AQA '']:[https://www.amazon.co.uk/gp/product/0008158770/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158770&linkCode=as2&tag=nrjc-21&linkId=ec31595e720e1529e49876c3866fff6e ''Resistors in parallel, pages 55, 63, GCSE Physics; Student Book, Collins, AQA '']:[https://www.amazon.co.uk/gp/product/0008158770/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158770&linkCode=as2&tag=nrjc-21&linkId=ec31595e720e1529e49876c3866fff6e ''Resistors in series, pages 54, 57, 63, GCSE Physics; Student Book, Collins, AQA '']:[https://www.amazon.co.uk/gp/product/1471851354/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851354&linkCode=as2&tag=nrjc-21&linkId=9012a0d354024419214fb3ad5ac44ba0 ''Resistors, pages 293, 295-6, GCSE Combined Science Trilogy 1, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/1471851370/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851370&linkCode=as2&tag=nrjc-21&linkId=01c69b0ae058f809cf636033e6ba793e ''Resistors, pages 40-1, GCSE Physics, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/019835939X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=019835939X&linkCode=as2&tag=nrjc-21&linkId=57e96876985fc39b1a3d8a3e3dc238b6 ''Resistors, pages 52-53, 55, 58-59, 61, 70, GCSE Physics; Third Edition, Oxford University Press, AQA '']:[https://www.amazon.co.uk/gp/product/1782946403/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782946403&linkCode=as2&tag=nrjc-21&linkId=32a0abb60dff015b15b50e9b1d7b4644 ''Resistors, pages 60, 66, 77-79, GCSE Combined Science Trilogy; Physics, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1782945970/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945970&linkCode=as2&tag=nrjc-21&linkId=a120d24dcc7cc7a58192069a3aafc1d2 ''Resistors, pages 62, 68, 79-81, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1471851370/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851370&linkCode=as2&tag=nrjc-21&linkId=01c69b0ae058f809cf636033e6ba793e ''Resistors; circuit symbol, page 38, GCSE Physics, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/1782946403/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782946403&linkCode=as2&tag=nrjc-21&linkId=32a0abb60dff015b15b50e9b1d7b4644 ''Resistors; I-V characteristics, pages 65, 66, GCSE Combined Science Trilogy; Physics, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1782945970/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945970&linkCode=as2&tag=nrjc-21&linkId=a120d24dcc7cc7a58192069a3aafc1d2 ''Resistors; I-V characteristics, pages 67, 68, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1782946403/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782946403&linkCode=as2&tag=nrjc-21&linkId=32a0abb60dff015b15b50e9b1d7b4644 ''Resistors; light-dependant resistors (LDRs), pages 60, 80, 81, GCSE Combined Science Trilogy; Physics, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1782945970/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945970&linkCode=as2&tag=nrjc-21&linkId=a120d24dcc7cc7a58192069a3aafc1d2 ''Resistors; light-dependant resistors (LDRs), pages 62, 82, 83, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1471851354/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851354&linkCode=as2&tag=nrjc-21&linkId=9012a0d354024419214fb3ad5ac44ba0 ''Resistors; light-dependent (LDRs), pages 299-300, GCSE Combined Science Trilogy 1, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/1471851354/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851354&linkCode=as2&tag=nrjc-21&linkId=9012a0d354024419214fb3ad5ac44ba0 ''Resistors; ohmic and non-ohmic, page 298, GCSE Combined Science Trilogy 1, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/1471851370/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851370&linkCode=as2&tag=nrjc-21&linkId=01c69b0ae058f809cf636033e6ba793e ''Resistors; ohmic and non-ohmic, page 43, GCSE Physics, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/1471851354/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851354&linkCode=as2&tag=nrjc-21&linkId=9012a0d354024419214fb3ad5ac44ba0 ''Resistors; thermistors, pages 298-9, GCSE Combined Science Trilogy 1, Hodder, AQA '']:[https://www.amazon.co.uk/gp/product/1782946403/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782946403&linkCode=as2&tag=nrjc-21&linkId=32a0abb60dff015b15b50e9b1d7b4644 ''Resistors; thermistors, pages 60, 80, 81, GCSE Combined Science Trilogy; Physics, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1782945970/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945970&linkCode=as2&tag=nrjc-21&linkId=a120d24dcc7cc7a58192069a3aafc1d2 ''Resistors; thermistors, pages 62, 82, 83, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1782946403/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782946403&linkCode=as2&tag=nrjc-21&linkId=32a0abb60dff015b15b50e9b1d7b4644 ''Resistors; variable resistors, pages 60, 65, GCSE Combined Science Trilogy; Physics, CGP, AQA '']:[https://www.amazon.co.uk/gp/product/1782945970/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945970&linkCode=as2&tag=nrjc-21&linkId=a120d24dcc7cc7a58192069a3aafc1d2 ''Resistors; variable resistors, pages 62, 67, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA ''] ====Edexcel==== :[https://www.amazon.co.uk/gp/product/1782948163/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782948163&linkCode=as2&tag=nrjc-21&linkId=0fdbfd5dd397d6e24a9dfb250f08587f ''Resistors (fixed), page 228, GCSE Physics, CGP, Edexcel '']:[https://www.amazon.co.uk/gp/product/1292120223/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120223&linkCode=as2&tag=nrjc-21&linkId=068ecf40278c32406a7f1c6e66751417 ''Resistors; parallel circuits, page 147, GCSE Physics, Pearson Edexcel '']:[https://www.amazon.co.uk/gp/product/1292120223/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120223&linkCode=as2&tag=nrjc-21&linkId=068ecf40278c32406a7f1c6e66751417 ''Resistors; series circuits, pages 146-147, GCSE Physics, Pearson Edexcel ''] ====OCR====:[https://www.amazon.co.uk/gp/product/0198359837/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0198359837&linkCode=as2&tag=nrjc-21&linkId=3c4229e8b023b2b60768e7ea2307cc6f ''Resistors, pages 104, 106, 110, 113, Gateway GCSE Physics, Oxford, OCR '']:[https://www.amazon.co.uk/gp/product/1782945695/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945695&linkCode=as2&tag=nrjc-21&linkId=ceafcc80bcad6b6754ee97a0c7ceea53 ''Resistors, pages 176, 178, 179, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR '']:[https://www.amazon.co.uk/gp/product/1782945687/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945687&linkCode=as2&tag=nrjc-21&linkId=9a598e52189317a20311d7a632747bc9 ''Resistors, pages 45-47, Gateway GCSE Physics; The Revision Guide, CGP, OCR '']