LDRs and Thermistors in Circuits - GCSE Physics

This video explains how we can use LDRs and thermistors in circuits in more detail. The reason you should know about these components is because they can be used in sensing circuits, to change what happens if it gets too hot, cold, dark or light.

We need to understand how these types of circuits work and how changing the resistance of a component in the circuit can change the current flowing through other components and hence either turn them on or off. Both LDRs and thermistors are variable resistors. LDRs' resistance decreases with increasing light intensity whereas thermistors' resistance decreases with increasing temperature.

LDRs are used in circuits on top of street lamps in order to turn them on when the sky gets dark. Thermistors are used in circuits in phones in order to stop them overheating and in kettles to turn them off when the water reaches boiling point.

Thanks for watching,

Lewis

Relevant for GCSE Physics 9-1 in the following exam boards:
AQA (including Trilogy)
Edexcel
OCR A
OCR B
WJEC
CIE (Cambridge International Examinations) IGCSE (Higher only)
Edexcel International IGCSE

_____________________________________

MY PHYSICS WEBSITES
Find even more videos organised by exam board and topic at:

GCSE Physics Online
A Level Physics Online

MY YOUTUBE CHANNEL
Your support in watching this video has been invaluable! To contribute towards the free videos on YouTube, make a small donation at:

FOLLOW ME

#thermistors #gcsephysics #physicsonline

[ninagething]

finally!! morning of my GCSEs and I finally understand how LDRs work, thank you!

[LearnToMaster]

Brilliant explanation. Thanks. Trying to explain to my children - it's all about the voltage in series changing. Not the current.

[franmarszalek]

woah I think I finally understand how LDRs work. Thanks!!

[henrusk]

Very Useful, best explanation ive heard

[airplanevibes]

Absolutely amazinf, cleared all components

[aadilmiah]

but if the resistance inreases does it not mean less currents flowing through so how does it get brighter

[shreysomani]

But I thought brightness of a light bulb depends on the current flowing through it not the voltage for gcse level

[idrk]

But why does a component get more potential difference if it has more resistance?

[xkl-physics]

In the dark does total current in the circuit decrease as total reistance increases ? Also p.d is shared in proportion to R

[jamessteward]

Does physics online reply
Ps it’s my birthday today