1. Class 12th Physics | Electrostatics | Electrostatics | by Ashish Arora

1. Class 12th Physics | Electrostatics | Electrostatics | by Ashish Arora


dear students lets start with a topic of electrostatics.
in electrostatics we can simply state it is the study of. interactions. and electrical
effects. due to. static charges that is charges at rest. mainly in this particular topic we
are going to deal only with static charges that’s why it is termed as electrostatics.
so very first thing we are going to study about is. charge, and its characteristics.
there are few facts which we need to understand and discuss. one by one we, just take it up
. like the very first thing is what do you mean by charge we can simply state. that charge
is a property . of, a matter. due to which. electrical and. magnetic effects are produced.
in your early classes you might have studied about electricity and magnetism. and all kind
of electrical and magnetic effects are produced by property on a matter, which is termed as
a charge. we know well that, all matter are composed of , atoms. so we can simply state
all matter . in a surrounding, which we can see, we can simply say all matter composed.
of atoms. and if we talk about an atom we can simply state an atom consist of two part,
one is its nucleus. and other is its extra nuclear part in which there are , electrons.
electrons are negatively charge which we all know , and nucleus consist of some particles
which we call nucleons, and majority of . the nucleons and nucleus are protons and neutrons
other nucleons are not in. our, syllabus or we can say it is beyond the scope of these
lectures that’s why i am not discussing about other nucleons that will discuss in
details of particle physics. and you know well that protons are positively charged and,
neutrons are neutral. and when we talk about charging of a body , if we just talk about
. charging . of a body, or body can be charged we can simply state , a body can be charged
by, addition or. removal of electrons. from it. like if we are having a body. and if we
remove some electrons from the body . and if some electrons are removed as the body
is neutral. we can simply state when electrons are removed this will be positively charged
. as an atom is electrically neutral and the body is made-up of neutral atoms so earlier
it was neutral and if some electrons are, removed from the body it’ll become positively
charged. similarly if on a body some electrons . are supplied. so these will be access electrons
in the body due to which we can say it’ll be . negatively charged. so to charge a body
the simplest way out is by addition or removal of electrons. and sometime students might
thing why cant we charge a body by addition or removal of protons. this quit difficult
because protons are there inside the nucleus and , it requires excessive amount of energy
to remove a proton from a nucleus. and free protons in nature . it is very difficult to
achieve because, these are either in case of, hydrogen ion or in case of some bound
state that we’ll discuss later in nuclear physics. next point we can talk about charges
is. which all of you are aware about that is . like charges. ripple each other. and
unlike charges . attract each other. there are some more properties lets continue on
next sheet. another fact about charges we can write down is, that is charge, is a scalar
quantity. it is not have any direction . only magnitude we talk about. another important
point about charge is , charge. is always quantize. in nature when we talk about, transfer
of charge we must, keep in mind that it is . not continues. whenever we supply charge
from one body to another . it must be in terms of electrons like if there is a body. and
we remove some electrons from the body it attains a charge q, q is the symbol we denote.
and, electrons. is a fundamental elementary particle, of which the charge is 1 point 6
into ten to power minus 19 coulomb. so whatever charge the body will attain will be a multiple
of this electronic charge so we can write q is equal to n e. where n belongs to set
of integer. here we can say whatever charge a body can attain will be an integral multiple
of, the electronic charge. so we can simply state charges always quantize . always. it
can have. discrete values. so always remember on physical object whenever charge is supplied
it must be , an integral multiple of electronic charge only that’s why we can say it is
not continues it is quantized. another point about charge we can say that. charge is conserved.
for which we already discuss that, an atom is electrically neutral . so whenever a charge
is created by removal of electrons from a body body will get positively charged and
equal , amount of negative charge will be there . due to removal of electrons. so we
can simply state charge is conserved, it can. neither be created . nor destroyed. so we
can say always. equal quantity of . positive and negative charges. can appear or disappear.
that means whenever charge neutralizes its equal quantity of opposite charge . then charges
will disappear . and equal quantity whenever these are generated like the examples we have
discuss that will always be in equal quantity only. and another important point about charges
we can say . charge is. invariant. for which we can say charge. does not depend on. reference
frame. in which reference frame you, just have a look on a charge body its charge always
appear to be same, in general we are talking about. in different cases will talk about
. other properties related to charge which may also vary , depending on reference frame
. but when we talk about charge it is invariant.