What is a Capacitor? (Physics, Electricity)

Capacitors are essential components of the electric and electronic circuits present in the technology we use every day. Students usually encounter capacitors for the first time in grade 12 physics class but often find capacitors and the way they work quite unclear.

In this video, we will dive into the fundamental knowledge related to capacitors: What are capacitors? What are capacitors used for? What is their role in a circuit and what happens physically during a charge or discharge of a capacitor.

This video is just an introduction to capacitors. It is not extensive. There are many relevant concepts we just mentioned without developing. These will be discussed in more detail in future videos (dielectric material, capacitance, time constant etc.).

#physics #capacitor #electricity

Structure of the video:
00:00 Introduction
00:30 What is a capacitor?
01:27 What are capacitors used for? (high power devices, phone chargers, signal filters)
04:11 What is an electric potential? What is a voltage? (Reminder of electricity basics)
05:08 What is an electric field? (Reminder of electricity basics)
05:28 How does a capacitor work? (What physically happens during the charging of a capacitor)
06:51 How does a capacitor work? (How can a current flow through a capacitor?)
11:51 How does a capacitor work? (What physically happens during the discharging of a capacitor)
12:57 What is a capacitor? (Conclusion)

In order to fully grasp the content of this video, the viewer needs to be familiar with the following concepts already presented in a PME video.
_ Electric Potentials.
_ Electric Fields.
_ Work.
_ Energy.

Note about conventional notations in electric circuits:
In this video (and all other videos about electricity), we use a conventional representation of electric circuits. In that model, the charges that are free to move are positive. Those that are fixed are negative. This model is used in most textbook and by the scientific community initially for historical reasons, but mostly because it is more convenient (no negative signs to handle) and because this model is mathematically and energetically equivalent to reality.

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This video is produced and presented by Edouard Reny, Ph.D. in solid state chemistry and private tutor in Physical Sciences.

[varshinispace]

This is the best physics channel one could ever get on Youtube....everything is perfect abt these videos

[Shivamkumar-vrnq]

I never seen a teacher like you sir, you are a genius sir thankyou sir for clearing my concept

[BI-kmdl]

Thank you! I see from other comments that you humbly resist being called a genius. This is understandable, especially in the world of physics, considering the likes of Newton, Einstein, Tesla, and so on. Still, the art of teaching is another discipline unto itself. To know your discipline well AND be able to teach it to a wide variety of people is its own kind of genius. Some of the world’s most gifted people in their respective fields can and do sometimes lack the ability to teach effectively. You sir, are NOT one of those people. Thanks so much for the considerable effort you’ve put forth to not only know your discipline well but also to make it accessible to idiots like myself!

[avadhkhandelwal]

Thankyou for this. Much appreciation for ur hardwork and help in understanding these concepts clearly

[jabbariqra]

Sir you explain all the basic phenomenat very clearly ..thank u

[xeku]

I am a jee aspirant and this video helped me to improve my conceptual understanding of capacitors . Thank you

[kuldeepkhajuria]

Please make more videos on electricity.Your video helps to understand the concept better.

[iwantacupoftae]

Great work as usual of course!! Keep going ❤

[peleghkx]

Thank you, You are a Wonderfull teacher ! you video is clear, understandable and make even the most complicated topics to look like a walk in the park.

[A-Karim]

big thanks and respect for the easy explanation

[WodahPaul-jpcy]

your videos are very explicit in explanation sir

[dalenassar]

At about timestamp 5:45 there is a, somewhat unknown, use for this circuit (since the cap is first in line). Suppose the switch is in the MIDDLE position and the capacitor is totally discharged. IOW the potential on both cap terminals is 0V. Now, keeping in mind that the VOLTAGE across a cap can not change instantly (just as the CURRENT in an inductor can't change instantly), if you flip the switch to the battery (say it's 12v), then the BOTTOM of the cap, as well as the top is instantly 12v, since there is no potential DIFFERENCE between the plates. Now the top plate of the cap STAYS at 12v, while the bottom plate 'charges' the cap through the resistor by going toward 0v via the RC rate.
This is a GREAT way to apply a fast 12v pulse to switch on an SCR, etc. without any timing circuitry...here a hi-value resistor can be placed across the cap for auto-reset (the cap used in this type of circuit is usually very small...~0.01uF. to 0.1uF).
I have used this method, and have also seen complicated circuitry where this would have greatly simplified it.
A great example of combined knowledge in the academic and typical circuit app of a capacitor from the FIELD point of view!
THANKS AGAIN,
--dALE

[anjali..]

Thanku for this amazing I am very confused with some topics of physics because i am not able to feel what is going on ..but ur videos help me a lot to understand each and every thing 💕💕 thank u again
Make more content we love it... 👍

[nohdahyun]

My physics teacher himself cannot explain like this... thank u

[anass]

teacher at 8:21 we considered that Vc=0 because no charges has arrived yet on the capacitor .but why Vr has a value?, why we didnt consider that no charges have arrived on the resistor also ?
i hope that you clarify this for me .

[Guys-sv]

these comments need more likes this video needs to be known

[jamestanny]

This was a little more complicated video on circuits and rather a rapid introduction to different aspects of electricity while the first 2 videos in this serie started slow and beginner friendly

[dhyana]

Sir, please make a video on Inductor. It's the most confusing concept for many. Please.

[leoygdf]

12:24 initally Vc is epsilom but why is Vr epsilom initially if when we charged the capacitor Vr went down to 0. I understand you said kirchoffs 2nd law but i dont get how Vr suddenly changed from 0 to epsilom Thanks

[bholaprasad-]

8:13 question ask in neet 2016, 2019 exam