Hi free science lessons. I've just finished my exams last week and id just like to give a really big THANKS to u for helping me revise with ur vids- they've been a great help!
Usually when I give an example, it's to illustrate a point. In most cases, you don't have to actually learn them (although it can't hurt). However, if you are specifically meant to know an example then I'll make that clear in the video.
Sir I’m struggling with the principle of the voltage decreasing as the temperature rises. At higher temperatures the resistance of the thermistor plummets so therefore less energy is needed to drive a current through the thermistor (I get this part). But doesn’t a lower resistance mean the current through the thermistor should increase? V=IR, so if the value of R rises while the value of I falls, why don’t they cancel each other out?
@Tom K I don't know would it help you or not now. But you are wrong. At night, the resistance of the LDR on the garden decreases. And this means it now has a low share of the pd. And this must mean that the other component must have a high share of the pd. And because pd is essentially the energy dropped per unit charge, we can say that the lamp (the second component - not the thermistor) has a high pd and so more energy is transferred to the lamp and because of this, it lights up at night. Look at the diagram - easy peasy lemon squeezy
@@arnoahmed9269 True, but it's actually based on how the circuit is made, a resistor is added in parallel to the lamp so that means overall resistance is smaller than the smallest individual resistor. So more energy can be transferred for every coulomb of charge to the lamp.
@@arnoahmed9269 In low light intensity the resistance of the LDR increases. They are inversely proportional. But yes the example of the garden light doesn't make much sense. A phone screen seems like a better example, as you would want it dim in the night.
Then you would you have the component e.g. the lamp connected across (in parallel) with the thermistor because now the thermistor has greater share of the pd and so more energy is transferred to the component (light),
A thermistor is made from a semiconductor.... A key feature for all semiconducting materials is that the resistance decreases as temperature increases. You can see that in diodes as well as in LDR's (low light intensity basically means low temperature). However, a filament lamp is not made from a semiconducting material so in that case its resistance increases as temperature increases. I hope that solves your question.
Is it different depending on whether its a heating or cooling system. Surely if it's hot there will be a high resistance to stop current flowing and letting the heater turn on as it's not needed. Vice versa for if its cold. And if you have a cooling system then like you say when it's hot there will be low resistance to let the current flow and the fan to work? please reply soon sir I have my Mock tomorrow, thank you!
You only need to know about a thermistor and LDR in terms of specialised components, low temperature= high resistance, high temperature = low resistance. In the fan when it's cool the thermistor takes most of the pd meaning most of the energy is transferred to the resistor, but when it's hot the thermistor has a low resistance meaning more pd is used to transfer energy to the fan.
These resistors are specialised, when there's a higher temperature in the thermostat it allows for current to flow through more easily with the PD as the pushing force
i am confused. i get that at high temperature the thermistor will have less resistance. however wont the high temperature cause the resistance to increase due to more energy being needed to push the current through the charged particles?
They are placed in parallel. The circuit is still a series circuit as a whole, because voltmeters being in parallel don't affect the circuit (you just ignore it). You just add in another little circuit where you want to place the voltmeter (as it cannot be placed in the actual series circuit) but you still count the circuit as a series circuit.
Hi free science lessons. I've just finished my exams last week and id just like to give a really big THANKS to u for helping me revise with ur vids- they've been a great help!
What ya doing now?
@@UnKnown-bg7jh this guy is asking the right questions
Tell us what you're doing now
@@brigadierbraveheart3173 crying cos of corona
@@_-_-_-_-__--_-_-_ hahaha mood
Your videos are beyond helpful, you have made this hard concept so easy to understand honestly it’s been a huge help so thank you so so much!
16 dislikes from the fans that only got 0.1 voltage
Thanks, I’ve made notes on this so hopefully I can remember it:)
Haha me to I realy hope I don’t forget the notes I made😂📝
you need active recall with spaced repetition to memorise notes - just making them wont help with memorisation at all - you have to use them properly
@@arakurd6351 you’re a bit late but... appreciate the thoigjt
thought*
@@idonthaveachannelname6585 thanks. just thought other people who would see this would be helped by comment.
Shawn mate, thanks for the videos. Love you xx
do we need to know about these examples like the incubator and computer? And any examples you do in your videos?
Usually when I give an example, it's to illustrate a point. In most cases, you don't have to actually learn them (although it can't hurt). However, if you are specifically meant to know an example then I'll make that clear in the video.
Hiya, do we need to know these examples in detail for the exam? Thanks :)
Yes you do 🙂
Sir I’m struggling with the principle of the voltage decreasing as the temperature rises. At higher temperatures the resistance of the thermistor plummets so therefore less energy is needed to drive a current through the thermistor (I get this part). But doesn’t a lower resistance mean the current through the thermistor should increase? V=IR, so if the value of R rises while the value of I falls, why don’t they cancel each other out?
The current is constant, meanwhile the resistance decreaes. Hence, the voltage must fall as well, as they are directly proportional
legend
Basically the opposite of filament lamp
Hehe my exam is in 3 hours :)
how can you be so CALM
How’d the exam go
Hehe I’m in my exams
0:37
doesnt it have a low resistance in dark conditions so there is more PD to light up lamp???
No ,,, dark conditions= low light intensity ... and low light intensity= high resistance ... so less PD to lamp,,, and less energy to light it up ,,
@Tom K I don't know would it help you or not now. But you are wrong. At night, the resistance of the LDR on the garden decreases. And this means it now has a low share of the pd. And this must mean that the other component must have a high share of the pd. And because pd is essentially the energy dropped per unit charge, we can say that the lamp (the second component - not the thermistor) has a high pd and so more energy is transferred to the lamp and because of this, it lights up at night. Look at the diagram - easy peasy lemon squeezy
@@arnoahmed9269 True, but it's actually based on how the circuit is made, a resistor is added in parallel to the lamp so that means overall resistance is smaller than the smallest individual resistor. So more energy can be transferred for every coulomb of charge to the lamp.
@@arnoahmed9269 In low light intensity the resistance of the LDR increases. They are inversely proportional. But yes the example of the garden light doesn't make much sense. A phone screen seems like a better example, as you would want it dim in the night.
is it THERMISTOR OR THER-MISTOR cuz seans version is werid
Thanks a lot may god bless you
No problem and thanks for your comment.
2023 gcse gang where u at
wassup! doin some easter revision as well? i'm doing aqa combined
exams in 30 minutes😭
can thermistors be used for electric thermometers?
Bless this man
BIG UP SHAWN
?
Wdym “big up shawn”?
Great summary.
How would thermistors be used to turn on a component when it is too cold?
You would use a parallel circuit like the one for LDRs.
Then you would you have the component e.g. the lamp connected across (in parallel) with the thermistor because now the thermistor has greater share of the pd and so more energy is transferred to the component (light),
Why is it that in a filament lamp resistance increases with temperature but in a thermistor resistance decreases with a temperature increase?
A thermistor is made from a semiconductor.... A key feature for all semiconducting materials is that the resistance decreases as temperature increases. You can see that in diodes as well as in LDR's (low light intensity basically means low temperature). However, a filament lamp is not made from a semiconducting material so in that case its resistance increases as temperature increases. I hope that solves your question.
Quick question where is the link for your revision workbook? @Freesciencelessons
melanie nabiikyi I think the workbook is being released in 2018
Not that you need it now but there now available on his website 👍🏽😂
Do you have a full video course for the Physics?. Please advise
Yes all of the GCSE Physics videos are in the playlists, covering the whole AQA spec.
2:44 me!
(I was born 15 weeks premature)
omg same!!
Thx so much bro 👊
CAN I WATCH THESE VIDEOS FOR {IGCSE} TOO?
I got igcse too. If you look at your spec online most of the stuff is the same as these videos :)
Is it different depending on whether its a heating or cooling system. Surely if it's hot there will be a high resistance to stop current flowing and letting the heater turn on as it's not needed. Vice versa for if its cold. And if you have a cooling system then like you say when it's hot there will be low resistance to let the current flow and the fan to work?
please reply soon sir I have my Mock tomorrow, thank you!
You only need to know about a thermistor and LDR in terms of specialised components, low temperature= high resistance, high temperature = low resistance. In the fan when it's cool the thermistor takes most of the pd meaning most of the energy is transferred to the resistor, but when it's hot the thermistor has a low resistance meaning more pd is used to transfer energy to the fan.
Why does the resistance decreases when the temp increases in a themistor? I thought the higher the resistance the more vibrations inside??
These resistors are specialised, when there's a higher temperature in the thermostat it allows for current to flow through more easily with the PD as the pushing force
@Freesciencelessons is the cooling fan necessary?
Its more an example to understand the concept
do we need to know the examples?
i am confused. i get that at high temperature the thermistor will have less resistance. however wont the high temperature cause the resistance to increase due to more energy being needed to push the current through the charged particles?
In a conventional resistor that would be the case but a thermistor is designed to be the opposite.
@@Freesciencelessons thankyou, I understand it now!
i thought that voltmeter were places in parallel 1:55 omg science got more confusing
They are placed in parallel. The circuit is still a series circuit as a whole, because voltmeters being in parallel don't affect the circuit (you just ignore it). You just add in another little circuit where you want to place the voltmeter (as it cannot be placed in the actual series circuit) but you still count the circuit as a series circuit.
Quick Question Sir, What are these 9-1 on the title ? (I am new to Cambridge syllabus so I have no clue)
Hi. It's what we call the new GCSE specification, because the grades now are 9-1.
Freesciencelessons
Oh, thank you
can u pls make for gates
do you have to know these circuits for aqa?
Yes
Hi everyone
thank you :)
Cool video! But you didn't make vids about logic gates pls make them thx 🙂
i’ll update w my exam results
so...
Where are the results ☠️☠️☠️
You can now update us
Come on lad I’ve been waiting 2 years
Thanks so much
Gcse 2021 gang where u at scicne set one
thanks
He is my grade saver
Interesting
Thank you ; )