Sensors: Direct Sensing - A Level Physics Part 2

[@waldo200399]

You literally have made every topic in A level sounds easier! You did an incredible job on explaining every single detail on the topic... Thanks a lot for your effort!

[@sahanmaddumage6641]

GREAT TEACHER!!!!, ive learnt more in the past half an hour than i have in the past few weeks with my teacher at school !!! thanks alot for these vids

[@effatulrazali3409]

why have I only found this video a day before my CIE exams. Such a great video.

[@DrPhysicsA]

Thanks. Hope the exam went well.

[@effatulrazali3409]

Thank you!

[@AizadJamil98]

Effs Fang how did it go? grades?

[@effatulrazali3409]

Aizad Jamil *sobs*

[@aniani135]

I'm studying Alevel physics myself and I have no idea how I'd do it without your videos.Thank you so much for all the videos

[@amit98616]

HI , i look ur videos everyday. U ar running a free school , which is helpful to indian students , especially for those , who cannot afford private coaching after school or college. A great social work, i salute u for this. PLEASE upload a separate video for OP-AMP and digital electronics. THANKS.

[@reignmore]

Appreciate the time and effort it takes one of these videos thanks for the thought !!!

[@DrPhysicsA]

Thank you. That is most gratifying. I have a video on logic gates which should give you some information about what you are asking.

[@DrPhysicsA]

What I am saying is that because there is no straight line connection between the resistance in the circuit and the thing which is varying then you have to do some form of calibration. If for example you want to switch on the light when the light levels in a room fall to a certain amount you will need to do an experiment to establish what level of resistance is needed such that when the light levels fall to the critical amount the output of the operational amplifier changes direction.

[@DrPhysicsA]

The output voltage is split across R1 and Rf. The actual voltage fed back to the amplifier is the voltage across R1 (ie voltage above 0v or ground voltage). So the proportion is R1/(R1+Rf).

[@842Mono]

this amplifier thing has very strange and strong a power to make me lose concentration!!! I totally lost concentration with my Dr in class so I thought I'd get help from here and oh my God I see stars!! about 7 times to pause the video so far

[@omsushantkarki]

i have decided not to be an electrical engineer

[@leenmaher2641]

MOOD

[@DrPhysicsA]

Open-loop gain of op amp is gain when no feedback is used in the circuit. Closed loop (or gain) does have feedback. Ao is the open loop gain. Vout is the output voltage of the op amp and Vin is usually the difference between the 2 input voltages.

[@hamnachaudhary4657]

In LED current could pass through both diodes to emit light. Then why at 18:15 when Vout was negative the current was unable to pass through second diode into the electromagnet to turn the switch on.

[@aceacetamide206]

Great Video that make me understand the whole chapter of direct sensing !

[@DrPhysicsA]

Have you seen my playlist on "A level Physics revision" which contains a number of videos on electricity and electromagnetism?

[@DrPhysicsA]

I am uploading a video on Logic Gates now. Should be available in a couple of hours.

[@fms9601]

thanks a lot Dr. Physics. You have always helped me understand difficult topics and made them very easy to me. Thanks again and keep it up :)

[@sheikhspear6725]

the only question i have how does that paper not end

[@DrPhysicsA]

Its actually A3 paper.

[@sheikhspear6725]

ahh i see that explains a lot :)

[@hamnachaudhary4657]

😂😂😂

[@PranavManShrestha]

Did you get help from the Application Physics support booklet of Cambridge A-Levels? Thanks so much for the explanation.

[@maazahmedpoke]

what's the purpose of the resistors in series woth the diodes at 20:19 mark?

[@ahmedak_1]

Thanks Sir, that was very well explained and made everything pretty much crystal clear for me :)

[@ynnad7778]

You have helped me immensely. Thank you so much

[@DrPhysicsA]

I'll have a go at a basic introduction.

[@colossalko]

I'm an amateur in circuits so this flew over my head. =(

[@ahmadhassan3684]

excellent explanation Dr physics

[@mothgods]

Hey doc, just wondering, whats the difference between Gain and Open loop gain? and Ao and Vout/Vin. thanks a lot!

[@comprehensiveboycomprehens8786]

Being honest a lot of this is still confusing because of a natural tendency to think of electricity as a flow of electrons which somehow does the business. Thinking of voltage as a dearth or surfeit of electrons seems to add to the confusion and the role of the earth is not explained not to mention conventional current direction. It seems you have to think of it as a kind of applied maths with certain rules but without a physical intuition. I think it's because electronics was developed before the physics of electrons was understood. I mean, charge ? If anyone feels the same I'd appreciate a reply comment.

[@hduoawbdo221]

Sir, I'm a bit confused - at 10.42, isn't beta supposed to be equal to Rf/(Rf+R1) instead of R1 being the numerator there as shown? I'm not also really being able to understand the essence of how these devices are functioning. What I mean to say is that I'm taking it for granted that the signal is being inverted but not really comprehending why.

[@yasser8118]

Thanks a lot for the videos sir. Very easy to understand :)

[@syedasabajilani1649]

Dr could u please tell me does your playlist follows Cambridge syllabus for A Levels please reply sir

[@TipiHensem]

Nicely done ! Thank you very much !

[@xyz39r1abc]

Dr could you please upload a vedio about electric fields and what's potential difference and how is electric fields linked to circuits ( the potential difference )

[@djsonu07]

Hello sir.. Can I ask you what is the purpose of an inverting or non inverting amplifier? Does that mean using only the inverting part or non inverting part of the amplifier? So, can't we have an amplifier with just an inverting part or non inverting? Am just confused and lack some information.. Please help me.

[@amanhussain322]

Thank you so so so so so so so so so so much !

[@jeanmarkd12345]

Hey Doc. Could you upload a video about Logic Gates. Thanks

[@needsum12love]

Thx you sir you are so kind i cant understand what my teacher is teaching but after watching ur 2 vids i was like enlightened, but could you explain more about back emf?

[@DrPhysicsA]

I cover this to some extent in my video Resistance, Reactance and Impedance

[@needsum12love]

thx agn

[@waliyahossain2665]

Sir, there have been some changes to the Physics Syllabus recently, will you be adding those changes to your videos soon?

[@DrPhysicsA]

+Waliya Hossain My A level revision series is an amalgam of the material for AS and A2 physics for the exam boards AQA, CIE, OCR and Edexcel. I'm not aware of anything completely new being introduced but please let me know if there is material which is missing.

[@ahmadhassan3684]

DrPhysicsA for example that Doppler effect

[@RogerKeulen]

Thanx for explaining electronics ! (Never can't have enough electronics :-)

[@xyz39r1abc]

I'm taking A level physics , but I'm really having a big problem in understanding electricity . How is electric field is linked with circuits ,

[@alevelsdemystified3410]

Btw shouldnt the gain formula for the,non inverting amplifier be 1 +R1/Rf?

[@Jayce1712]

Dude im in love you you! Thank you so much!

[@zatulmutalif3230]

doc..HELP ME PLEASE!!! i dont understand the part u said about calibrate..esp for the last 21-22 minutes..help me pleaseeeeeeee

[@xyz39r1abc]

I'll check it out ,

[@xyz39r1abc]

Thanks in advance .