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===Meaning===
[[File:VariableResistorSymbol.png|right|300px|thumb|The symbol for a '''variable resistor'''.]]
A '''variable resistor''' is a [[resistor]] which can have its [[Electrical Resistance|resistance]] changed.
===About Variable Resistors===
: A '''variable resistor''' can be used to control the [[Electrical Current|current]] passing through a [[circuit]]. If the [[Potential Difference|potential difference]] is constant then the [[Electrical Current|current]] decreases as the [[Electrical Resistance|resistance]] of the '''variable resistor''' increases.
: A '''variable resistor''' can be used to control the [[Potential Difference|potential difference]] of another [[Electrical Component|component]] in [[Series Circuit|series]] with it. If the [[Electrical Resistance|resistance]] of the '''variable resistor''' is increased the [[Potential Difference|potential difference]] across other [[Electrical Component|components]] will decrease.
{| class="wikitable"
|-
|[[File:PotentialDivider1.png|center|200px]]
|[[File:PotentialDivider2.png|center|200px]]
|[[File:PotentialDivider3.png|center|200px]]
|-
| style="height:20px; width:200px; text-align:left;" |In this [[circuit]] the '''variable resistor''' has a [[Electrical Resistance|resistance]] of 0Ω.
The [[Potential Difference|potential difference]] across the fixed [[resistor]] is 6V.
The [[Electrical Current|current]] through this [[circuit]] is given by:
<math>I = \frac{V}{R}</math>
<math>I = \frac{6}{5}</math>
<math>I = 1.2A</math>
| style="height:20px; width:200px; text-align:left;" |In this [[circuit]] the '''variable resistor''' has the same [[Electrical Resistance|resistance]] as the fixed [[resistor]] (5Ω).
The [[Potential Difference|potential difference]] across the fixed [[resistor]] is 3V.
The [[Electrical Current|current]] through this [[circuit]] is given by:
<math>I = \frac{V}{R}</math>
<math>I = \frac{6}{10}</math>
<math>I = 0.6A</math>
| style="height:20px; width:200px; text-align:left;" |In this [[circuit]] the '''variable resistor''' has twice the [[Electrical Resistance|resistance]] of the fixed [[resistor]] (10Ω).
The [[Potential Difference|potential difference]] across the fixed [[resistor]] is 2V.
The [[Electrical Current|current]] through this [[circuit]] is given by:
<math>I = \frac{V}{R}</math>
<math>I = \frac{6}{15}</math>
<math>I = 0.4A</math>
|}
===Examples===
{| class="wikitable"
|-
|[[File:VariableResistor.png|center|100px]]
|[[File:Rheostat.png|center|300px]]
|-
| style="height:20px; width:300px; text-align:center;" |This '''variable resistor''' can be turned to change the [[Electrical Resistance|resistance]].
| style="height:20px; width:300px; text-align:center;" |This '''variable resistor''' is known as a [[Rheostat]]. The slider can be moved to change [[Electrical Resistance|resistance]].
|}
===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 ''Variable resistor, page 52, GCSE Physics; Student Book, Collins, 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 ''Variable resistors, circuit symbol, page 38, 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 ''Variable resistors, pages 293, 296, GCSE Combined Science Trilogy 1, 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 ''Variable resistors, pages 52-53, GCSE Physics; Third Edition, Oxford University Press, AQA '']
====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 ''Variable resistors, page 105, 113, Gateway GCSE Physics, Oxford, OCR '']