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Topics covered in this Capacitor Class 12 lecture by ABJ sir IITD with timestamp:

00:00 04:03 Force on Dielectric: ABJ sir explains two cases of dielectric medium b/w plates. If the dielectric medium is completely inserted b/w plates, the net force on the dielectric medium will be zero. But, if the dielectric medium is partially inserted b/w plates, the net force on the dielectric medium will be nonzero.
04:04 09:06 Capacitance due to partially inserted dielectric medium: In past lectures, we learned the formulae of capacitance when the medium is a vacuum. ABJ sir derived the capacitance formula when a dielectric medium partially inserts b/w plates. ABJ Sir used Formulae of parallel combinations of capacitors to find the capacitance.
09:25 16:02 Fixed Potential difference across Capacitor: A battery is connected to this capacitor, and now a dielectric inserts. ABJ sir derives the attraction force formula using the potential energy gradient.
17:04 25:40 Capacitor Problem 1: In this problem, we have two plates of length l and width b at the separation of d distance. These plates are connected to a battery of E volts. Now a dielectric medium inserts of dielectric constant k and mass m. We have to find the acceleration of the dielectric, the maximum velocity of a dielectric, and the time period of oscillation. To solve this problem, ABJ sir used the formula of force on the dielectric medium. As we know, F=ma, So the acceleration value can be found easily, and maximum velocity will be when the dielectric is fully inserted b/w plates.
26:15 30:25 Fixed Charge on the Capacitor: In this case, no external voltage source is connected to the plates, but the charge on the plates is fixed. Now a dielectric inserts b/w these plates and we have to find the value of force on the dielectric. Similarly, as in the last case, Force equals the gradient of potential energy, and we get a value of force that is not constant.
30:40 36:41 Capacitor Problem 2: In this problem, we have a liquid of dielectric constant K, and two plates of length l and width b at the separation of distance d connected to a battery of voltage E. This system of plates is dipped with the constant velocity v into liquid. We have to find Force on the dielectric at any time t. Also find the charge on the capacitor and current in the circuit.
37:14 42:35 Capacitor Problem 3: In this problem, we have two plates of length l and width b at the separation of distance d connected to a battery of voltage E. Water level is increasing b/w this plates with the constant velocity v. This system of plates is dipped with the constant velocity v into liquid. We have to find the charge value on the capacitor and current in the circuit at any time t. To solve this problem, ABJ Sir used the formula of a Series combination of two capacitors. At time t, there will be a water layer of thickness 'vt' and rest vacuum, So it will behave like two different capacitors of different capacitance.
43:05 48:18 Combination of parallel Metallic plates: This is very important type of problem wrt JEE Mains & Advanced. To explain this concept, ABJ Sir used an example in which there are 4 parallel metallic plates.


This is the Eighth lecture of Capacitor / Capacitance class 12 for JEE Mains & Advanced. There are a total of 10 lectures in one shot for Capacitor class 12, in which ABJ sir is covering all topics, concepts, examples, and problems that are important for JEE Mains and Advanced.

This Capacitors class 12 Physics lecture consists of the Force on the dielectric in two different cases , first Fixed potential difference across capacitor and second Fixed charge on the capacitor. ABJ Sir discussed the problem related to force on capacitor in this lecture. This lecture is for the Science student of class 12 who is preparing for JEE Mains & Advanced or Olympiad. ABJ sir also covered JEE ADVANCED PYQ in this lecture.

Prerequisite of the chapter : Electrostatics Class 12
Playlist of Electrostatics Class 12
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