Electrostatics starts with the basic idea of charged particles and their properties. Know about simple experiments to demonstrate various things. Charged body can be made by charge induction or rubbing. Know about three basic properties of charges – additive, conservation and quantization of charges.
Then comes Coulomb’s law which tells about amount of force due to two charged particles. This depends on charge of bodies and distance between them. As force is vector quantity, we have to take its components during calculations. Electric field but force exerted by charge on unit charge at given distance. In short it is associated with only one charge. It is also vector quantity so it follows vector addition.
Field lines for positive charges emerge out where for negative charge, concentrate inward. Now, the concept of electric flux comes which tells about concentration of field lines through given area. It’s the scalar quantity with dot product of two vector quantities. Electric dipole is pair of equal and opposite charges separated by small distance. Overall charge on dipole seems to be zero but electric field is not. It can be calculated from basics. If it is placed in external field it will experience torque.
Same concepts will be applicable for continuous charge distribution by using integration on entire body. The Gauss’s law makes electrostatics easily. Generally it is used to calculate electric field usually for symmetrical things. Last concept is about electric potential. It is work done per unit charge. If we know potentials at two points then we can compute work required in moving charges. It’s the scalar quantity.
Equipotential surfaces is plane with all points at same potential. Work done will be zero on this plane. From this potential energy comes, which is work done in bringing two charges from infinity to given distance between them. Know about electric field, potential etc. on conductor.
General mistakes/challenges-
- In this topic sign hold much importance as it gives type of force. So be caution with signs.
- Many find dipole problems difficult but solve them from basics, it’ll be easier.
- In Gauss’s law, there is total charge needed i.e. effective charge in area.
- While solving problems, first see direction of electric field, potential gradient and which charge you are dealing. Then solve it systematically.
Tips/guidelines-
- Focus mainly on flux, Gauss’s law, dipole and potential problems.
- For electric field use Gauss’s law wherever possible as it’s easy.
- Understand expressions of electric field and potential for various cases. Don’t mug.
- In dipole’s case, remember expressions like energy, potential. But it’s always good to know concept.
- Solve types of problem on potential and work done, because it’ll decrease common mistakes.
- Study about how field lines will look in different arrangements of charges.
- Prepare theoretical points because you may confuse in them.
This is basic for other related topics as we study static charge here. Build your skills in this. Focus on main concepts and reduce common mistakes then you can command this.
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