Hello students  now let’s start at the very interesting topic of physics paper Two yes words will be starting with the topic called electrostatics now student this particular topic has been divided into several modules but in the initial view modules will be revising the concepts that we have learned and standard 11th and then only will be starting with the concept of standard 12th so let us begin with the first module and in this particular module will be learning term call charge right but before starting with the term called charge let us analyze the word called electrostatics right now if i divide this particular word i can divide in two section and the first section says electro which refers to a word called charge and second one is static which means at rest so in this particular chapter will be learning the effects produced by the charges at rest so if i want to defined a word called electrostatics i can define it as a study of charge or system of charges at rest is called as electrostatics right so there’s nothing but the definition of a word called electronics right now let’s start with the term called charge on let us define the word called charge now student charge is nothing but the fundamental property of matter by the virtue of which two bodies can either attract each other or they can repel each other so it is nothing but the fundamental property right now what is the unit of charge do we know yes we know is a unit of charge what is SI unit the SI unit of charge is Coulomb what is CGS unit the CGS unit of charges start Coulomb  or electrostatic unit of charge which is also written as e.s.u and the relation between one Coulomb  and e.s.u is 1 Coulomb  it is equal to 3 into 10 raise to power 9 e.s.u  right now let us write the dimensions for charge now we do doing no formula for charge yes we have learned formula of charge Q is equal to IT where I is electric current and t is nothing but time right and we’re using this particular formula i can write dimensions of charge as a I raise to power one and t raise to power 1  right let us revise the values of charge on the fundamental particles right what are the three fundamental particles the three fundamental particles are electron proton and neutron right so what is the value child an electron the value of charge on electron is – 1.6 *10 power minus 19 coulomb right what is the value of charge proton on the value of charge on proton is 1.6 *10 raise to power minus 19 coulomb and the value of charge of neutron is zero Coulomb  so students if we know the total number of protons and electrons in a given body we can calculate the amount of charge in that case right now strong if any uncharged body loses electrons then it will become yes it will become positively-charged and if any uncharged body gains electrons then that particular body will become negatively charged right now these are the few important points Kindly  noted down now let us move further let us revise the properties of Charge now the first property is charged is a scalar quantity right or i can say charge can be added like normal mathematical numbers right so let’s take an example I’m having first body which is positively charged having charge plus 6 Coulomb   second body which is negatively charged having charge equal to minus -5 Coulomb  so if i calculate net charge in this particular case in this case net charge will be 6 – 5 which is equal to 1 Coulomb  right so what we have Learned we have learned that charges here are being added just like scalar numbers right so this is the first property and the second property is conservation of charge we have already learned law of conservation of charge and what does it says it says charges can neither be created nor destroyed right and it will always remain conserved in an isolated system right so let’s take an example let’s say I’m having first body which is positively charged having charge equal to plus 6 Coulomb second body which is negatively charged having charge equal to minus 4 Coulomb right so what will be next child in this case in this case net charge will be plus 6-4 and that is nothing but equal to plus 2 Coulomb i like to make the wire between these two boodies a little bit transfer of charge right from one body to another body right so after transfer of charge let’s say the value of charge on the individual body becomes plus 4 Coulomb  and minus 2 Coulomb  so again store and if i calculate net charge net charge will again come out as plus 2 Coulomb  rights students so i can say here the value of charge on the individual bodies are changing but the net charge on and system on an isolated system remains constant or concept right so this is nothing but the second property of charge which says conservation of charge right now let’s move was the third property which says charge is always quantized or it is nothing but quantization of charge and it says charge on anybody can only be an integral multiple of 1 .6 *10 raise to power minus 19 coulomb right or any charge can be written as q is equal to plus minus ne right where n is any integer and e is nothing but the fundamental charge which is nothing but it will do 1.6 *10 based power minus 19 coulomb right so this suggests that charges like + e , -2 e + 4 E is certainly possible but the charges like 0.5 e and 1.3eis not at all possible so students in this particular module we have simply revised the term called charge and we have also revised the properties of charge as well right that’s it for this module I’ll see you in the next part of till then keep learning.