Republic of the Philippines
CEBU TECHNOLOGICAL UNIVERSITY
Cebu City Mountain Satellite Campus
Sitio Maomawan, Babag, Cebu City 6000 Philippines
ctu.ccmsc@ctu.edu.ph
( RA 11185 )
Name:
Subject:
Stephanie D. Borres
Course/Year/Section: BSED SCI 2-2A
Electricity and Magnetism Lecture
Instructor:
Nancy G. Largado
Activity for Magnetism
A. Give a summary of the video about magnetism
 Magnet is an object that has a special property to attract certain materials such as iron, nickel
and cobalt, steel but not attracted to stainless steel. Magnets have two poles North Pole and
South Pole. If magnet is suspended freely using a string, then the pole that points towards the
North Direction is called the North Pole and the pole that points towards the South Direction
is the South Pole. The different shapes a magnet are bar magnet, horseshoe magnet and disk
magnet.
 Properties of Magnets are (1) like poles repel each other. North Pole of the two magnets are
repelling each other similarly the two south poles will also repel each other. (2) Unlike poles
attract each other. North pole of the magnet attracts the South Pole. (3) Monopole cannot
exist in a magnet it must have two poles. For example, if you break a magnet into two parts
each part will have two poles a North Pole and a South Pole.
 Magnets attract objects by inducing opposite polarity on the object and so induction
precedes attraction.
 Magnet has a magnetic field around it. Magnetic field is strong near the magnet and it
becomes weak far away from the magnet. The strength of the magnetic field decreases as the
distance from the magnet increases.
 A magnetic field can be visualized using magnetic field lines and the pattern of the magnetic
field lines tell us the shape of the magnetic field
 To find the shape of the magnetic field there are two ways using iron filings and a magnetic
compass.
 Properties of Magnetic Field Lines are (1) the magnetic field lines start from the North Pole
and end at the South Pole. (2) The magnetic field lines come close to one another near the poles
of the magnet they are densely packed at the poles but the field lines are more widely separated
at other places. (3) The magnetic field lines do not intersect each other.
 Earth's magnetic field (and the surface magnetic field) is approximately a magnetic dipole,
with the magnetic field S pole near the Earth's geographic north pole and the other magnetic
field N pole near the Earth's geographic south pole. This makes the compass usable for
navigation
 The SI unit used to measure magnetic field is Tesla and the symbol is T
 The average value of the Earth's magnetic field on the surface of the earth is only about 50
micro Tesla so the magnetic field near a bar magnet is about 200 times stronger compared to
the Earth's magnetic field on the surface of the Earth and it’s pretty weak.
 What would happen if magically the Earth's magnetic field became very strong then imagine
all the iron objects being attracted towards the earth. The earth has a bar magnet placed inside
it but actually there is no real magnet inside the earth so how does
 Earth gets magnetism it's because due to the magnetic effect of electric current. And the
electric currents are due to the motion of convection currents of molten iron in the Earth's outer
core and the electric currents produce magnetism so the earth is like a huge electromagnet