GCSE Physics - Electricity 4 - Relays, LDRs and Thermistors
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- เผยแพร่เมื่อ 23 พ.ค. 2017
- A GCSE revision video designed to help you learn about more advanced components like LDRs thermistors and diodes, and their use in relays and rectifiers. Suitable for iGCSE and GCSE revision.
The best and fastest explanation I found. Thank you very much!
Thanks! Check out my other videos too, and good luck in your GCSE exam!
So true !!
Thank you so much, it was a short but very simple and effective explanation!
I habe a premock on Monday and I'm do nervous, our teacher rushed us to complete the syllabus while we don't understand anything, this is helping me a lot Thank you so much!! I can't express how helpful you are!!
this video is extremely helpful, thank you!
🔥🔥have been looking for it all the day thank you 💞
that was a FULL and SIMPLE explanation.....thanksss
made me understand really quick thanks for the tutorial :)
thankyou for clearing my concept a day before exams
We found the actual gigachad.
Thank you
Finally I get it!
You are a gifted teacher. Thanks for making difficult lessons so easy. Best Wishes from Singapore @@///////18/8/2021
Thanks for the comment! Glad the video was useful!!
thank you for this explanation
Amna Khushnood you’re welcome! Thanks for commenting :)
05:20 How does the switch pop back open?
tysm:)
Wouldnt the path consisting of an electromagnet would lead to a short circui? If that happens, current will be provided a resistance free path and thus would flow in that path rather than the the thermistor itself
Im confused af
thank yoouuuu
Day of exam, thank you for explaining
Glad I could help!!
Hi. I want to ask fabout the transistor as a amplifier, why the loud speaker is placed above the collector in the circuit but not below the emitter in the circuit...
Jia Ee I’m not really sure which circuit you are talking about... when using a transistor as an amplifier, the transistor takes a weak signal (a signal in this case is a fluctuating current and a weak signal would mean it fluctuates from zero to a small value) and basically transfers the signal to a circuit with a higher voltage, therefore producing current fluctuations between zero and a higher value than before. Of course, the speaker has to be in the second part of the circuit so it receives the stronger signal. Hope that helps!
@@lovattphysics6366 ok thank you very much 💙
Hey, can you explain why in a thermistor/LDR the resistance decreases as the temperature/light intensity increases? Cause I've been searching and I've found that in some cases, the resistance increases as temperature increases as shown in the transformer chapter. (where high voltages are used in power grids to decrease the current and the heating effect which ultimately decreases resistance, as high heating effect which means high temperatures will result to a higher resistance) Waiting for your enlightenment! (My physics theory is next week, so i hope you can give me a quick response) Any help is appreciated, thanks!
Good question! It is to do with the material they are made of. As they get hotter/more light, it releases more free electrons inside the material, and if there are more electrons then (simply) more electricity can be conducted so there is less resistance. Hope that helps!
U saved me
I, will come over later ❤
Why does the voltage decrease but not the current?
Good question! The current would change slightly too, in reality, because the total resistance of the circuit is changing. But with these potential dividers, we are really focused on the difference in voltage, because the voltage is the amount of energy being transferred to the coil to open the switch. Hope that helps!
Why do you need the other resistor in the circuit ?
Monika_1604 Vlogz great question! You need the other resistor because the output voltage Vout is controlled by the ratio of the two resistors. The fixed resistor is where the “other”voltage goes. If you only had the thermistor, the voltage output would always stay the same (although the current would change)
LovattPhysics Thank you :)
greatly explained! however could u pls make video on relays and for the logic gates control system??
Shabaz Ul Haq yep there is a logic gate video here: th-cam.com/video/1BatDVYLNzI/w-d-xo.html
why would u use v equals to IR with thermistor, it is non ohmic material
BushStudies good question. Whenever we are using V=IR in this situation we are assuming that the temperature of the thermistor is staying constant during the measurement and calculation. Hence the resistance of the thermistor is staying constant at that time. You’re right though, if the temperature was fluctuating during the measurement, the resistance would also fluctuate, making V=IR invalid. This method only works when comparing different CONSTANT temperatures. Hope that helps!
I have a question.
Aren’t voltage and current two different quantities?
When resistance in thermistor decreases the amount of current ( I ) increases and the voltage (V) decreases. Am I right?
The Legend voltage and current are two different quantities yes! The current is slightly more complicated because the resistors are in series, so if the resistance in the thermistor decreases then the total resistance of the circuit decreases and so the current will increase, yes. But it is really the voltage that we pay attention to in potential dividers. Hope that helps!
LovattPhysics Hey just a question.
Can you make a video on Cathode Ray Oscilloscope?
The Legend ill add it to my list. A cathode ray oscilloscope is just an oscilloscope (the cathode ray bit just tells you the kind of display it is). An oscilloscope is a tool used to analyse wave forms by displaying them on a screen.
I'm confused at around 2:50. I thought that as resistance decreases, the current increases, and therefore the voltage increases. So why does the voltage decrease as the resistance decreases? I understand that the equation makes sense, but logically, I can't understand that bit... any help would be much appreciated! Thank you
Lizzie Coldrick remember that the voltage across both resistors (together) is staying the same, and that resistors in series share the voltage, so the voltage across resistor 1 plus the voltage across resistor 2 equals the voltage from the battery. Now, think of the voltage as the amount of energy that the current needs to get through the resistor. A bigger resistance will need a bigger amount of energy to get through, right? So if one of the resistors decreases, then this resistor will need a smaller share of the total voltage. A smaller resistor needs a smaller amount of energy to get the current through it. Does that make sense?
@@lovattphysics6366 That makes much more sense now! I have never understood that before, so thanks so much for that explanation
Lizzie Coldrick awesome, glad I could help! Any more questions just ask :)
@@lovattphysics6366 Actually, I did have one more question. It isn't on the GCSE syllabus that I'm studying now, but I was wondering what the difference between Faraday's law and Lenz's law is...
Lizzie Coldrick good question! First, lets start with the idea that a current in a wire creates a magnetic field around it. Faraday’s law says that the reverse happens too - a magnetic field induces a current in a conductor. But the key thing is the magnetic field has to be CHANGING (e.g. if the magnet is moving closer to the conductor). Faraday’s law says that the size of the induced current is proportional to the change in magnetic field. Lenz’s law says that when this happens, the induced current always flows in such a way that it resists the change in the magnetic field. In other words, Faraday’s law predicts the size and Lenz’s law predicts the direction of the induced current. Hope that helps!
Reminds me of ElectroBoom's "FULL BRIDGE RECTIFIER"! How many can relate?
Why does resistance decrease with voltage?
It’s more the other way round - the more resistance something has, the more energy the electrons need to get through it. Energy per unit charge = voltage! Hope that helps!
tnxxxxxxxxxxxxxxxxxx
Is this for grade nine or not
Dalia Yasser usually grade 10!
Litt
Sir wh6 did u stop uploading!
I don’t have as much time! But I will try to make more this year :)