Magnetic Effects of Electric Current Video Lecture | Science Class 7

magnetic effects of electric current we
have already learned about the heating
effects of electric current what could
be the other effects of electric current
do you know that an electric current
carrying produces a magnetic field
around it this property of electric
current is used in appliances like
transformer on the electric poles
electric water pump generator speaker
electric doorbell radio
on television large electromagnets are
used in scrapyard trains to separate
iron scrap from other metals let us
perform an activity to understand how
magnetic field is produced around
electric current carrying wire place a
large nail close to a few small iron
nails does this large nail attract be
smaller nails more now take about one
meter long insulated copper wire and
wind it round a large iron nail then
connect the ends of the wire to a
battery you will see that large iron
nail can attract tiny iron nail towards
it how small nails are attracted to the
large nail connected to a battery
without a magnet placed close to it let
us explore the reason for this the
reason is that an electric current
flowing in the wire has produced a
magnetic field due to which large iron
nail has turned into a magnet
this shows that electricity and
magnetism are linked to each other the
invisible force attracting the metals is
magnetic owes in this chapter we will
study about the magnetic fields and such
electromagnetic effect Hans Christian
ørsted
studied electromagnetism in the early
19th century
you found that a wire carrying electric
current generates a magnetic field
around it when a compass is placed near
the wire and the current is not flowing
the needle points to the Earth's
magnetic north when the current is
flowing the generated magnetic deflects
the DD this was first observed by Hans
Christian ørsted in 1820 and confirmed a
direct relationship between electricity
and magnetism
the unit of magnetic field strength is
named the oil said in his honor the
radio television and fiber optics are
based on our state's research let us
perform an activity to show our state's
experiment take a thick insulated copper
wire and fix the wire in not found
direction a plotting compass M is placed
under the wire a-b the two ends of the
wire are connected through a switch when
no current is flowing in the wire a-b
the compass needle is parallel to the
wire a-b
and points in usual lot south direction
now pass the electric current through
the wire a-b by pressing the switch on
passing the current compass needle is
deflected from its north-south direction
when the current is switched off the
compass needle returns to its original
position if we reverse the direction of
current flowing in the wire a-b
by reversing the battery connections the
compass needle is deflected in the
opposite direction the deflection of
compass needle by the current carrying
wire shows that the electric current
produces magnetic field around it and
this magnetic field deflects the compass
needle
before learning about magnetic field let
us first understand what a magnet is a
magnet is any object which attracts the
pieces of metals like iron steel nickel
etc magnet comes in various shapes and
sizes the most common is the bar magnet
how does this get its name as magnet the
ancient Greeks and Chinese discovered
that certain stones called lodestones
were naturally magnetized these stones
could attract a small piece of iron in a
magical way and always point in the same
direction when allowed to swing freely
suspended by a piece of string an object
having the properties similar to large
stone was named magnet the named magnet
comes from magnesia a district in
Thessaly Greece