How to light a bulb using a cell - Electricity And Circuits - CBSE Class 6 Science Video Lecture

hello kids a bulb is the most commonly
used source of light so today we shall
learn how to light a bulb using a cell
the bus fells petrol from the petrol
pump and thus petrol pump supplies it
energy then how does a cell supply
energy to bulb as you know bulb needs
electric current to glow and electric
cell produces electricity from the
chemical store inside it when we connect
the cell properly with the bulb the
chemicals produce electricity look at
the cell closely one side is marked plus
that is positive and the other side is
marked minus that is negative why is it
so if you observe the cell closely it is
a small metal gap on one side and a
metal disc on the other side the metal
disc is the negative terminal and the
metal cap is the positive terminal to
recognize the positive and negative
terminals of the cell easily one side s
mark plus and the other side is marked
minus all the electric cells have two
terminals a positive terminal and a
negative terminal and how does the
electric current flow reach the bulb
from the cell yes through the wires or
more precisely through the circuit
before that let us understand the bulb
which gives us light a little bit more
look at the bulb a little closer when it
is switched on a small piece of wire in
the middle of the bulb is glowing and
emitting light this small piece of wire
is fixed in the middle of the bulb it is
called filament the filament is fixed to
the two thicker wires which also
provides support to it one of these
thick wire is connected to the metal
case at the base of the valve the other
thick wire is connected to the metal tip
at the bottom Center
of the pace now how would we connect a
bug to a cell to make it glow if we just
connect any part of the bulb using wires
to the cell say the part made of glass
put the bulb glow no so there are fixed
places on the bulb which we have to
connect with the ends of the cell to
make the bulb glow the first place is
the screw marks on the metal base of the
bulb the second place is the tip of the
metal base of the bulb these places are
called terminals so like a cell the bulb
also has two terminals to reiterate the
base of the bulb and the metal tip of
the base are the two terminals of the
bulb both of these terminals have to be
connected to different ends of the cell
so that the current can flow through
both the terminals of the cell to make
the bulb glow now we know where to
connect the wires in a bulb
let us help the electric current to
reach the bulb otherwise cell would be
useless and wouldn't make the bulb glow
now let us make a path for electric
current to flow connect an electric wire
to the positive end of the cell we can
use rubber bands or tape to fix the
wires to the cell now connect the other
end of the electric wire with any
terminal of the bulb say we connect with
the terminal which is on the metal base
we can stick the wires to the bulb with
the tape used by the electrician's
we already know about conductors are
insulators so the tape and rubber band
are insulators and hence we use them for
fixing wires
we made arrangements for the current to
reach the bulb but still the bulb is not
glowing
why because the cell is not connected to
the second terminal
besides current cannot come back to the
cell so the circuit is not complete let
us make the path for current to flow
back to the cell by connecting the
negative terminal of the cell with the
other terminal of the bulb for this
connect a wire to the other terminal of
the bulb say the tip of the metal base
and connect the other end of this wire
with the negative end of the cell
look the bulb is glowing wow that means
the circuit is complete what if we
reverse the connection from the bulb to
the cell that is the terminal which was
connected to the negative terminal of
the cell is now connected to the
positive terminal of the cell and
vice-versa
well the bulb still glows that shows the
bulb does not have positive or negative
terminal like a cell we started making
the path from positive and ended at the
negative end of the cell not same end of
the cell what if we connect both the
terminals of the bulb with one end of
the cell only that is either both of the
terminals to the positive terminal or
both the terminals to the negative
terminal of the cell would the bug glow
it seems like it should glow because
there is a closed tour complete part
visible but the bulk phone glow in both
the cases and there is a valid reason
for it we are no current flows in a
fixed direction in the case of cell the
current flows from the positive end to
the negative end so we need to provide
that path between the positive
the negative end of the cell in order
that current flows through it current
reaches one terminal of the bulb from
the positive end of the cell and then
comes back to the cell through the wire
connected to the other terminal of the
bulb now we know both the terminals of
the cells need to be connected to the
bulb to provide the complete path for
the flow of electricity when we reverse
the wire connection from the bulk to the
cell still the bulb glowed how here
again in the cell the current flows from
the positive end to the negative end as
both the terminals of the cell are
connected to the bulb to provide the
complete part for the flow of
electricity what would happen if the
wire is cut at any point it should be
simple to answer now yes the current
will not be able to complete the tool
from the positive end to the negative
end of the cell going through the two
terminals of the bulb so current
wouldn't flow as there is no complete
path for it
hence the bulb would not glow coming
back to the story
it was just many bulbs a portable
battery to provide electricity to the
world and a switch to stop and start
lighting of the bulbs that did the trick
and the kidnappers ran away in fright
that was very funny indeed so now you
know how to light a bulb using a cell as
the source of electricity
both the terminals of the cell are
connected to provide the complete part
for the flow of electricity the
electricity flows from the positive
terminal of the cell to the negative
terminal of the cell but a word of
caution as electricity is dangerous
don't attempt to do it alone do it under
the supervision of adults and follow all
the safety measures by kids and have fun