 Okay, so the chapter name is Electrostatic Potential and in most of the books, in the way it is states one and electrostatic two. In electrostatic two, mainly they are talking about the capacitance. In NCRT is that they have club, electrostatic potential and capacitance. Okay, now potential, let me just give you some analogy of whatever we have done in class killer. For example, in class killer, there was this, we dealt with forces, we dealt with, we have considered, in fact, the effect of that, so always till normal most of the chapter, we have considered the effect of potential energy. Okay, we have treated potential energy in two different ways. Okay, so when you can, you know, study as two types. Okay, you can study the, you can study the effect or effect of that as an energy. Okay, and when we are, so all that we are going to study in this particular topic. Four or five of you were not there. Anyways, in gravitation potential energy can introduce new, we have first understood the effect of the charges as electrostatic force. Okay, potential energy that will be in this chapter. Okay, now before we even get into that, first do you know how we define the potential energy? What is the definition of potential? Do you know that? Potential energy. Potential energy. Okay, so inside, okay, so we know, we should know how can we derive the expression for potential energy for a particular force. Do you remember how we define the expression for potential energy for any force? Do you remember? How you used to define it? Define it. What do you mean by this? Define it once. I wanted to define the potential energy of a conservative force. What is the process of it which we are defining for our convenience? All right, so that we will be able to hide that. Now, tell me how much work is done by the gravity over here. If I move this hand from those changes with height, you can't multiply force with this specimen. Okay, for example, it changes. Okay, so you can't just multiply. And then force per unit charge was 3. Similarly here, first you will charge q1. Okay, both are u2-v1. U2's potential energy r1. This is equal to u2-v1. It will not change your answer because when you... In fact, it will not get affected because of that. Just 4 meters k in which is... If the distance between them is very large, the distance between the charges is very large. So that is true. Then potential energy will become equal to k times q1, q2 by r. This will be potential energy between the two charges. Okay, and mind you, this is not the potential energy of q1 or our potential energy of q2. This is the potential energy of... Even if you forget, it needs to be done to dismantle the system. So it will shell off charge, uniformly distributed, even though it is not a point charge. Outside itself, it will behave like a point charge only. So right now, potential energy is one sphere is uniformly distributed. So I am saying that they are insulator, the charge can't move itself. Once you fix the charge at a location, it will remain there only. Fine? So if q1, q2 by r... It will be... It will be... So x will be equal to 10 r divided by 1 plus minus u2. Now tell me 1 plus root 2... x is non-center. x. Okay? Understood? Solving these two, you can get the... Don't expect them in school, but don't get surprised.