Difference between revisions of "Thermistor"

Latest revision as of 16:45, 20 December 2019

Key Stage 4

Meaning

The symbol for a thermistor.

A thermistor is a resistor which changes resistance depending on the temperature.

About Thermistors

'NTC' thermistors decrease resistance as the temperature increases. (NTC = Negative Temperature Coefficient.)

A thermistor can be used to control the current passing through a circuit. If the potential difference is constant then the current decreases as temperature decreases.

A thermistor can be used to control the potential difference of another component in series with it. If the temperature is decreased then the potential difference across other components will decrease.

Thermistors can be used temperature sensors.

IV Graph

Description

The IV Graph for an 'NTC' thermistor shows that:

At a high temperature the current increases rapidly with the potential difference
At a low temperature the current increases slowly with the potential difference.

Explanation

The resistance of an 'NTC' thermistor increases as the temperature decreases.

Obtaining the IV Graph

	Connect an ammeter in series with the thermistor to measure current through the thermistor. Connect a voltmeter in parallel with the thermistor to measure the potential difference across it. Use a variable resistor in series with the thermistor to vary the potential difference across the thermistor. Place the thermistor in a beaker of cold water around 5°C. Start with a potential difference of zero and increase the 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 and current. Repeat steps 5-7 with the thermistor in a beaker of hot water around 40°C.

References

@@ Line 5: / Line 5: @@
 ===About Thermistors===
-: 'NTC' '''thermistors''' decrease [[Electrical Resistance|resistance]] as the [[temperature]] increases.
+: 'NTC' '''thermistors''' decrease [[Electrical Resistance|resistance]] as the [[temperature]] increases. (NTC = Negative Temperature Coefficient.)
 : A '''thermistor''' 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 [[temperature]] decreases.
 : A '''thermistor''' can be used to control the [[Potential Difference|potential difference]] of another [[Electrical Component|component]] in [[Series Circuit|series]] with it. If the [[temperature]] is decreased then the [[Potential Difference|potential difference]] across other [[Electrical Component|components]] will decrease.
 : '''Thermistors''' can be used [[temperature]] sensors.
+===IV Graph===
+{| class="wikitable"
+|[[File:IVGraphThermistor.png|center|400px]]
+|}
+====Description====
+The [[IV Graph]] for an 'NTC' [[thermistor]] shows that:
+*At a high [[temperature]] the [[Electrical Current|current]] increases rapidly with the [[Potential Difference|potential difference]]
+*At a low [[temperature]] the [[Electrical Current|current]] increases slowly with the [[Potential Difference|potential difference]].
+====Explanation====
+: The [[Electrical Resistance|resistance]] of an 'NTC' [[thermistor]] increases as the [[temperature]] decreases.
+====Obtaining the IV Graph====
+{| class="wikitable"
+|-
+|[[File:ThermistorIVGraphCircuit.png|center|300px]]
+| style="height:20px; width:300px; text-align:left;" |
+#Connect an [[ammeter]] in [[Series Circuit|series]] with the [[thermistor]] to measure [[Electrical Current|current]] through the [[thermistor]].
+#Connect a [[voltmeter]] in [[Parallel Circuit|parallel]] with the [[thermistor]] to measure the [[Potential Difference|potential difference]] across it.
+#Use a [[Variable Resistor|variable resistor]] in [[Series Circuit|series]] with the [[thermistor]] to vary the [[Potential Difference|potential difference]] across the [[thermistor]].
+#Place the [[thermistor]] in a [[beaker]] of cold [[water]] around 5°C.
+#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]].
+#Repeat steps 5-7 with the [[thermistor]] in a [[beaker]] of hot [[water]] around 40°C.
+|}
+===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 ''Thermistor, pages 47, 52, 64-5, GCSE Physics; Student Book, Collins, AQA '']
+:[https://www.amazon.co.uk/gp/product/1782945598/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945598&linkCode=as2&tag=nrjc-21&linkId=ad276ad49df77ab4b40ab4fd0fe10356 ''Thermistors, page 184, GCSE Combined Science; The Revision Guide, CGP, AQA '']
+:[https://www.amazon.co.uk/gp/product/178294558X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=178294558X&linkCode=as2&tag=nrjc-21&linkId=f0dfb66dafcb0c6e9449e7b1a4ae1ac452 ''Thermistors, page 27, GCSE Physics; The Revision Guide, CGP, 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 ''Thermistors, page 57, GCSE Physics; Third Edition, Oxford University Press, 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 ''Thermistors, pages 293, 298-9, 316-17, 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 ''Thermistors, pages 43-4, 64-5, 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 ''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 ''Thermistors, pages 62, 82, 83, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA '']
+====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 ''Thermistors, page 149, GCSE Physics, Pearson Edexcel '']
+:[https://www.amazon.co.uk/gp/product/1782945741/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945741&linkCode=as2&tag=nrjc-21&linkId=30da4f2178da182547b62a7329d13b57 ''Thermistors, page 187, GCSE Combined Science; The Revision Guide, CGP, Edexcel '']
+:[https://www.amazon.co.uk/gp/product/1782945733/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945733&linkCode=as2&tag=nrjc-21&linkId=2a2dbec9db6bf5766c0458d908fa0a52 ''Thermistors, page 74, GCSE Physics; The Revision Guide, CGP, 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 ''Thermistors, pages 225, 226, 229, GCSE Physics, CGP, Edexcel '']
+====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 ''Thermistors, page 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 ''Thermistors, page 47, Gateway GCSE Physics; The Revision Guide, CGP, 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 ''Thermistors, pages 108-109, 112, Gateway GCSE Physics, Oxford, OCR '']