Awesome explanation on the 'mathematics/calculus applied'. You are very patient and show all the details and review of the algebra and calculus substitutions of the physics involved. You are an AMAZING teacher.
I suggest u to study physics from physics wallah(indian youtuber) he's simple the best .. the only problem is that u won't understand him since he speaks hindi
For anyone confused about 4:03 where he simply adds a negative sign in front of the derivative, here is an explanation. The issue relates to the fact that, before the sign is added, dq / dt refers to the current through the resistor (a positive quantity, due to the passive sign convention) and therefore dq refers to a differential charge inside the resistor. Without applying the negative sign, you would be "mixing" your charges (or q's) by referring to both the charge in the capacitor and the charge in the resistor in the same equation (i.e. at this point q and dq do NOT refer to the same charges). If you want the term dq / dt to refer to the current through the capacitor (which is a negative quantity when it is discharging due to the passive sign convention) then you need to apply a negative sign in front of it, since dq / dt for the capacitor itself is negative, and the negative's "cancel" each other out to yield the correct KVL equation. A clearer way to have done it might have been to refer to the charge in the capacitor as qc, and the charge in the resistor as qr. Then you would simply substitute dqr / dt = - dqc / dt.
@@alexandredemasure Whenever using variables in an equation, independent of the sign before the variable, its obvious to see that the variable itself can "intrinsically" hold a negative sign, e.g. if I say -x = 3, x turns out out to equal -3 i.e. the negative sign was *inside* x itself. In the case of dq / dt for the capacitor, the quantity of dq / qt itself can be negative or positive, representative of negative current or positive current. Due to the passive sign convention, we represent positive current as a positive charge flowing through a component from the positive terminal to the negative terminal, and negative current as a positive charge flowing from the negative terminal to the positive terminal. For a resistor, charge always flows from the positive terminal to the negative terminal. However, for components such as batteries, charge flows from negative to positive when power is being provided to the circuit. When the capacitor is charging, the positive charges in the picture flow upwards and towards the negative terminal, however when we refer to the charge flowing "in" the capacitor we say it flows straight through from negative to positive. This represents a negative current, and therefore the "intrinsic sign" of dq / dt for the capacitor is negative. For the resistor current "i" in that equation, we can simply substitute dq / dt in place of i, because dq / dt is positive, and this matches our assumed sign for i, which is sort of positive by definition in this case. However, dq / dt is 'intrinsically negative' for the resistor, because of how the passive sign convention works. Therefore, if we want the equation which involves dq / dt to refer to dq / qt of the capacitor, we add a negative sign, therefore negating the intrinsic negative sign, and from then on dq / dt no "refers" to the capacitor. Hope this helps
Man you're a lifesaver, I had to do a project about this, I'm in 12th grade and 12th grade maths doesn't include integrals so my physics book didn't really explain that part? so it just jumped to the final formula and I was so confused. Great video, clear as day and really easy to understand.
@@sofiagodinho924 oh .. but they should include these portions as the calculus(derivatives and integrals) is the backbone of maths.. in india things are far more tougher in 12th grade...anyways good to know that u can speak English as I thought that latins only speak their native language😂😂.. I was wrong brother..
@@HamzaKhan-sl7wj Spanish people have a really hard time with english, in portugal most people have a really good grasp of the language and can speak it effortlessly, even though our accent is very heavy
It's not exactly based on the grade per se but rather the ability of the person. This specific video is for AP Physics C, which is a University/College Level Class taught in High School. People who take this class usually do some in 11th or 12th, but this is actually for first year physics in College
Current = rate of change of charge. Since the capacitor is being depleted here, the rate of change of charge is a negative quantity. That's why the current is negative.
Basically because there's a voltage drop across that resistor. Which is characterized by an energy loss. Kirchoffs analysis is basically a neat application of conservation of energy and voltage is of course potential energy per unit charge.
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Awesome explanation on the 'mathematics/calculus applied'. You are very patient and show all the details and review of the algebra and calculus substitutions of the physics involved. You are an AMAZING teacher.
Thank you so much for these videos. My ap physics class is taught really fast and I miss a lot of concepts but your videos help fill in the blanks.
Great video. Clear and to the point.
basically i can show you my phd ye
your videos are amazing! you should really consider making videos on additional topics like electromagnetic waves!! PLEASE PLEASE PLEASE!
keep up the good work....
Wow look what I've found! It's amazing! Thx!!
I suggest u to study physics from physics wallah(indian youtuber) he's simple the best .. the only problem is that u won't understand him since he speaks hindi
Thank you!!! It helped me a lot to understand this topic.
Thank you it helped a lot
For anyone confused about 4:03 where he simply adds a negative sign in front of the derivative, here is an explanation.
The issue relates to the fact that, before the sign is added, dq / dt refers to the current through the resistor (a positive quantity, due to the passive sign convention) and therefore dq refers to a differential charge inside the resistor. Without applying the negative sign, you would be "mixing" your charges (or q's) by referring to both the charge in the capacitor and the charge in the resistor in the same equation (i.e. at this point q and dq do NOT refer to the same charges).
If you want the term dq / dt to refer to the current through the capacitor (which is a negative quantity when it is discharging due to the passive sign convention) then you need to apply a negative sign in front of it, since dq / dt for the capacitor itself is negative, and the negative's "cancel" each other out to yield the correct KVL equation.
A clearer way to have done it might have been to refer to the charge in the capacitor as qc, and the charge in the resistor as qr. Then you would simply substitute dqr / dt = - dqc / dt.
Thanks, I had trouble with that. Not perfectly sure still why would the variation of charges be opposite between R and C.
@@alexandredemasure Whenever using variables in an equation, independent of the sign before the variable, its obvious to see that the variable itself can "intrinsically" hold a negative sign, e.g. if I say -x = 3, x turns out out to equal -3 i.e. the negative sign was *inside* x itself.
In the case of dq / dt for the capacitor, the quantity of dq / qt itself can be negative or positive, representative of negative current or positive current. Due to the passive sign convention, we represent positive current as a positive charge flowing through a component from the positive terminal to the negative terminal, and negative current as a positive charge flowing from the negative terminal to the positive terminal.
For a resistor, charge always flows from the positive terminal to the negative terminal. However, for components such as batteries, charge flows from negative to positive when power is being provided to the circuit. When the capacitor is charging, the positive charges in the picture flow upwards and towards the negative terminal, however when we refer to the charge flowing "in" the capacitor we say it flows straight through from negative to positive. This represents a negative current, and therefore the "intrinsic sign" of dq / dt for the capacitor is negative.
For the resistor current "i" in that equation, we can simply substitute dq / dt in place of i, because dq / dt is positive, and this matches our assumed sign for i, which is sort of positive by definition in this case. However, dq / dt is 'intrinsically negative' for the resistor, because of how the passive sign convention works. Therefore, if we want the equation which involves dq / dt to refer to dq / qt of the capacitor, we add a negative sign, therefore negating the intrinsic negative sign, and from then on dq / dt no "refers" to the capacitor.
Hope this helps
@@gvcallen Thanks a lot, very helpful
I came to see the comments looking for this. Thanks a lot !!
Thank you!
God bless you man
Thanks so much!
So you plugged Ohms law into derivatives to make the relationship seem more complex?
beautiful
very helpful, TY!
np awroight
You just saved my life thak you
YOU ARE THEREFORE HIS PROPERTY TO DO WITH AS HE PLAESES
Man you're a lifesaver, I had to do a project about this, I'm in 12th grade and 12th grade maths doesn't include integrals so my physics book didn't really explain that part? so it just jumped to the final formula and I was so confused. Great video, clear as day and really easy to understand.
12 grade maths doesn't include integration?wth ?which country ?
@@omop5922 it included derivatives but not integrals. Portugal
@@sofiagodinho924 oh .. but they should include these portions as the calculus(derivatives and integrals) is the backbone of maths.. in india things are far more tougher in 12th grade...anyways good to know that u can speak English as I thought that latins only speak their native language😂😂.. I was wrong brother..
@@HamzaKhan-sl7wj Spanish people have a really hard time with english, in portugal most people have a really good grasp of the language and can speak it effortlessly, even though our accent is very heavy
@@sofiagodinho924 what is the language there ?
good stuff!
hot stuff - julian wu 2015
i love you, great video
I love you
That's not an acceptable way of writing a q.
imfrommanndame p
ye go on
Excellent lecture 🙏🙏🙏🙏🙏
thank you so much sir
Thank you 😭
what are the steps of discharging a capacitor?
firstly you have to do the discharging/charging practical 15 million toimes roight
why is there no battery? also, how do you find the voltage across resistance when it is discharging?
The capacitor is the "battery". You can store charge in the capacitor.
@@tentanus3938 capacitors do not store charge. They store energy ma gueule.
in which grade do you guys take these?
+Firas Ghotmi Second year of college.
+Firas Ghotmi 11th
highschool or freshmen year of college
basically in year one class, although i was a 20 year old ye
It's not exactly based on the grade per se but rather the ability of the person. This specific video is for AP Physics C, which is a University/College Level Class taught in High School. People who take this class usually do some in 11th or 12th, but this is actually for first year physics in College
at 2:49 why is i negative?
Current = rate of change of charge.
Since the capacitor is being depleted here, the rate of change of charge is a negative quantity.
That's why the current is negative.
Basically because there's a voltage drop across that resistor. Which is characterized by an energy loss. Kirchoffs analysis is basically a neat application of conservation of energy and voltage is of course potential energy per unit charge.
If you were just talking about at 2:49 which is him setting up his equation. But Islam is definitely right about the capacitor being depleted.
shylildude Kirchoff Voltage Law
because basically you have to ask yourself what is charge
but why do you write Vc + Vr =0 , in normal kirchoff analysis wouldn't we write Vc - Vr=0?
he's right,since dq/dt is negative,thats why it becomes Ri+v(t)=0 .its correct .
basically ye
Why can't my proff teach it like this? It'd make so much more sense.
where is the battery?
Lol😂
333
your q looks like drunken 8 ! xD
YOU ARE A GHASTLY CHILD I AM NOT COVERED IN MY OWN GREASE
yeah
basically yeah
yeah its basically just a phd school
nothing more, nothing less
voltage source missing. ooops
+kenneth christie Not showing a voltage source indicates the capacitor is being discharged, and no charged. He's correct.
ye basically kenneth has done alot of work on potential ye
Your pen sound is annoying