Electric Current and Resistance
, Current &Resistance
The
topics we have studied so far is the
key to enter in a new world of
electricity where we can use
electricity in our daily life . We use Tv . fan ,
light bulb Computer , ,
mobile all runs with
electricity . But how can we produce
electricity ?
If we can move
charge in controlled an continuous manner we can produce
electric current which we can use to do work .
Here controlled and continuous way is
very important For example .
in case
of lightning a
huge amount of charge moves through atmosphere but we
cannot use it for doing work For the case of discharging
.
capacitor a
electric current is also produced in there but the flow of charges is
not Contini out .
When we realized that
electricity need not to be brief
spark or shock doors to the modern world opened .
You know an experiment of Galvani when he touched a dead frog's muck
with metal wire the muck of the frog moves .
A- I send ro Volta 's investigation
led
shortly to the invention of an
early battery .
cut Volta made a
pile of alternate metal
zn \
sheets
C U
IN
act cooked
paper separated by Nad soaked paper
the terminal wires
touching Tung
In
on we
-
gives a sensation of mild electric shock .
An important thing to note here that the electric shock is even mild
but the sensation
of the shock is lasted for longer time than a
capacitor .
Later Humphry Davy piled up large no of such sheets to produce a
spark You . can also do experiment with lemon and cu and Zn Plates to produce
electricity .
, Electric Current
Whenever charge in controlled and continuous way electric
moves a we
get
current . Let's
begin with a
simple Thustion how a
capacitor get discharged ?
If we connect the two capacitor Plates with a conductor the Plates .
Quickly becomes neutral , i. e. the capacitor has been discharged Charge .
has somehow moved from one plate to the other .
We define current
as the motion of charges It . seems that
capacitor has been discharged
by a current in the connecting wire .
If the wire is
very thin it gets
hot and sometime glows and current carrying wire deflects a
compass needle , as indicators that current is present in the wire .
The that conductor charge
charges moves in a are called carriers .
The model of metallic conductor reminds that the
microscopic us
outermost electrons bound to the
of a metal atom are
weakly nuclei
they are called Valance electrons -
they form a fluid like a sea of
electrons that can move
through a solid .
The metal as a whole remains
This perfect Quantum
electrically neutral .
is not a model we
ignored some
effects .
Electrons are the
charge carriers in metals ,
but in ionic
solution or semiconductor has different charge carriers .
In this chapter
we will focus on metals
only .
Creating Current Although an electric current is a stream
of moving
charges ,
not all
moving charges constitute an electric current . If there
is to be an electric current there must be a net flow of charge through
the surface .
For
example consider an isolated copper wire .
The free electrons in
, Current &Resistance
The
topics we have studied so far is the
key to enter in a new world of
electricity where we can use
electricity in our daily life . We use Tv . fan ,
light bulb Computer , ,
mobile all runs with
electricity . But how can we produce
electricity ?
If we can move
charge in controlled an continuous manner we can produce
electric current which we can use to do work .
Here controlled and continuous way is
very important For example .
in case
of lightning a
huge amount of charge moves through atmosphere but we
cannot use it for doing work For the case of discharging
.
capacitor a
electric current is also produced in there but the flow of charges is
not Contini out .
When we realized that
electricity need not to be brief
spark or shock doors to the modern world opened .
You know an experiment of Galvani when he touched a dead frog's muck
with metal wire the muck of the frog moves .
A- I send ro Volta 's investigation
led
shortly to the invention of an
early battery .
cut Volta made a
pile of alternate metal
zn \
sheets
C U
IN
act cooked
paper separated by Nad soaked paper
the terminal wires
touching Tung
In
on we
-
gives a sensation of mild electric shock .
An important thing to note here that the electric shock is even mild
but the sensation
of the shock is lasted for longer time than a
capacitor .
Later Humphry Davy piled up large no of such sheets to produce a
spark You . can also do experiment with lemon and cu and Zn Plates to produce
electricity .
, Electric Current
Whenever charge in controlled and continuous way electric
moves a we
get
current . Let's
begin with a
simple Thustion how a
capacitor get discharged ?
If we connect the two capacitor Plates with a conductor the Plates .
Quickly becomes neutral , i. e. the capacitor has been discharged Charge .
has somehow moved from one plate to the other .
We define current
as the motion of charges It . seems that
capacitor has been discharged
by a current in the connecting wire .
If the wire is
very thin it gets
hot and sometime glows and current carrying wire deflects a
compass needle , as indicators that current is present in the wire .
The that conductor charge
charges moves in a are called carriers .
The model of metallic conductor reminds that the
microscopic us
outermost electrons bound to the
of a metal atom are
weakly nuclei
they are called Valance electrons -
they form a fluid like a sea of
electrons that can move
through a solid .
The metal as a whole remains
This perfect Quantum
electrically neutral .
is not a model we
ignored some
effects .
Electrons are the
charge carriers in metals ,
but in ionic
solution or semiconductor has different charge carriers .
In this chapter
we will focus on metals
only .
Creating Current Although an electric current is a stream
of moving
charges ,
not all
moving charges constitute an electric current . If there
is to be an electric current there must be a net flow of charge through
the surface .
For
example consider an isolated copper wire .
The free electrons in
