Electric Charges and Fields ✏️ 📌NCERT PICKS 🔴 There is a spark or crackle when we take off oursynthetic clothes or sweater in dry whether. 🔴 It is observed that if two glass rods rubbed with wool or silk cloth are brought close to each other, they repel each other. 🔴 On rubbing two body, the mass of one body slightly get lowered. 🔴 An ebonite rod held in hand can be charged by rubbing with funnel but a copper rod cannot be charged like this. 🔴 When we touch a pith ball with an electrified plastic rod, some of the negative charges on rod are transferred. 🔴 While calculating the force between the two charges from coulomb's law, never take into account, the sign of two charges. It just indicates nature of the force. 🔴 The test charge used to measure electric field at point is taken as unit in magnitude or very small. 🔴 Field lines are always directed from higher potential to lower potential. 🔴 Neutral point is a point where resultant electric field is zero. 🔴 When a charged particle enters with velocity at right angle to the uniform field the trajectory is parabola. 🔴 A surface having same electric potential at every point is an equipotential surface. 🔴 Work done in moving a charge along an equipotential surface is always zero. 🔴 Relative permitivity of the material is also known as specific inductive capacitance. 🔴 Two charged spheres having