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Difference between revisions of "Variable Resistor"

(Created page with "==Key Stage 4== ===Meaning=== right|300px|thumb|The symbol for a '''variable resistor'''.")
 
 
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===Meaning===
 
===Meaning===
 
[[File:VariableResistorSymbol.png|right|300px|thumb|The symbol for a '''variable resistor'''.]]
 
[[File:VariableResistorSymbol.png|right|300px|thumb|The symbol for a '''variable resistor'''.]]
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A '''variable resistor''' is a [[resistor]] which can have its [[Electrical Resistance|resistance]] changed.
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===About Variable Resistors===
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: 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.
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: 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.
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{| class="wikitable"
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|-
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|[[File:PotentialDivider1.png|center|200px]]
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|[[File:PotentialDivider2.png|center|200px]]
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|[[File:PotentialDivider3.png|center|200px]]
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|-
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| style="height:20px; width:200px; text-align:left;" |In this [[circuit]] the '''variable resistor''' has a [[Electrical Resistance|resistance]] of 0Ω.
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The [[Potential Difference|potential difference]] across the fixed [[resistor]] is 6V.
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The [[Electrical Current|current]] through this [[circuit]] is given by:
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<math>I = \frac{V}{R}</math>
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<math>I = \frac{6}{5}</math>
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<math>I = 1.2A</math>
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| 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).
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The [[Potential Difference|potential difference]] across the fixed [[resistor]] is 3V.
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The [[Electrical Current|current]] through this [[circuit]] is given by:
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<math>I = \frac{V}{R}</math>
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<math>I = \frac{6}{10}</math>
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<math>I = 0.6A</math>
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| 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).
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The [[Potential Difference|potential difference]] across the fixed [[resistor]] is 2V.
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The [[Electrical Current|current]] through this [[circuit]] is given by:
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<math>I = \frac{V}{R}</math>
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<math>I = \frac{6}{15}</math>
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<math>I = 0.4A</math>
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|}
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===Examples===
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{| class="wikitable"
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|-
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|[[File:VariableResistor.png|center|100px]]
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|[[File:Rheostat.png|center|300px]]
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|-
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| style="height:20px; width:300px; text-align:center;" |This '''variable resistor''' can be turned to change the [[Electrical Resistance|resistance]].
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| 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]].
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|}
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===References===
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====AQA====
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:[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 '']
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:[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 '']
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:[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 '']
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:[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 '']
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====OCR====
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:[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 '']

Latest revision as of 10:41, 25 December 2019

Contents

Key Stage 4

Meaning

 
The symbol for a variable resistor.

A variable resistor is a resistor which can have its resistance changed.

About Variable Resistors

A variable resistor can be used to control the current passing through a circuit. If the potential difference is constant then the current decreases as the resistance of the variable resistor increases.
A variable resistor can be used to control the potential difference of another component in series with it. If the resistance of the variable resistor is increased the potential difference across other components will decrease.
 
 
 
In this circuit the variable resistor has a resistance of 0Ω.

The potential difference across the fixed resistor is 6V.

The current through this circuit is given by\[I = \frac{V}{R}\]

\(I = \frac{6}{5}\)

\(I = 1.2A\)

In this circuit the variable resistor has the same resistance as the fixed resistor (5Ω).

The potential difference across the fixed resistor is 3V.

The current through this circuit is given by\[I = \frac{V}{R}\]

\(I = \frac{6}{10}\)

\(I = 0.6A\)

In this circuit the variable resistor has twice the resistance of the fixed resistor (10Ω).

The potential difference across the fixed resistor is 2V.

The current through this circuit is given by\[I = \frac{V}{R}\]

\(I = \frac{6}{15}\)

\(I = 0.4A\)

Examples

 
 
This variable resistor can be turned to change the resistance. This variable resistor is known as a Rheostat. The slider can be moved to change resistance.

References

AQA

Variable resistor, page 52, GCSE Physics; Student Book, Collins, AQA
Variable resistors, circuit symbol, page 38, GCSE Physics, Hodder, AQA
Variable resistors, pages 293, 296, GCSE Combined Science Trilogy 1, Hodder, AQA
Variable resistors, pages 52-53, GCSE Physics; Third Edition, Oxford University Press, AQA

OCR

Variable resistors, page 105, 113, Gateway GCSE Physics, Oxford, OCR
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