dear students lets start with the topic of
electric current. and, in your early classes
you might have studied about the basic definition
of current in which, we write that. rate of
flow of charge. through. any cross section.
of a conductor. in which current is flowing
obviously we are talking about. is called.
electric current. to understand the basic
analysis of current in various circuit, here
you can have a look on this situation. when
we are given with a cylindrical conductor.
connected wire, perfectly conducting wires
with the battery and a switch. here you can
see when we closed down the switch. positive
terminal of battery will pull free electrons
of the conductor which will start flowing
through the wires. in anticlockwise manner.
And a continues flow of, electrons exist.
and, in the process of current flow battery
has to do a continues work. or we can say
battery has to supply a power, that is work,
per unit time. to maintain the current in
the circuit. and due to these flow of electrons,
we can say. a current exist in this circuit,
in clockwise manner because conventionally
you know that the direction of current flow,
is opposite to the flow of, electrons. or
direction of flow of current is considered.
as the direction of flow of positive charges.
that is the convention we use. now if we just
talk about the magnitude of current this can
be written as rate of flow of charge delta
q by delta t. if delta q amount of charge
is flown, through any cross section, in a
time delta t. say if we can say if, n electrons.
pass. through a section. in time delta t then,
here we can state charge flowing. can be written
as, n-e. where e is the charge of electron
and n are the total number of electrons which.
passed. through a given section. Then, i can
be written as n e by delta t. or for a continues
flow of charge this current can be written
as d-q by d-t. which we can also termed as,
instantaneous current. in the situation where,
the rate of flow of charge is not constant
it is varying we always defined instantaneous
current. and the whole analysis related to
current is done by the. this, time derivative
of charge flowing, in the. conductor in which
we are calculating the current.
