Magnetism is the property of changed particles in
motion due to the spin of electrons within the
atoms. It is a property of materials that respond
to an applied magnetic field.
Electromagnetism is the study of the interaction
between electrically charged particles and
magnetic fields.
A magnet is an object that can attract or repel pieces
of materials with magnetic properties. The magnetic
field is the area that a magnet influences.
Retentivity
Ability of a magnetic material to retain its
magnetism after it has been magnetized
Magnets were named after Magnesia, in Asia
Minor, where the Greeks discovered metallic
rocks that could attract metal and other rocks.
Early peoples called magnets lodestones. These
stones were used in navigation as compasses,
therefore they were called lodestones, from the
words lode (meaning course or way) and stone.
Classification of Different Magnetic
Materials
1. Ferro Magnetic- Substances that are highly
attracted by magnets
2. Non-Ferro Magnetic – non-magnetic substance
3. Diamagnetic – materials are slightly repelled
by a magnet
4. Paramagnetic – slightly attracted by powerful
magnets
Classification of Magnets
1. Natural
2. Artificial
3. Electromagnet
General Properties of Magnets
1. Magnets usually have two poles
2. Like magnetic poles repel and unlike poles
attract
3. A piece of magnetite when made to hang freely
would align itself with the magnetite field of the
earth following the N.S. direction
4. Permanent magnets are magnets made from
alloys of cobalt and nickel
5. Other metal like iron can be magnetized by
interaction
Causes of Magnetism
1. Molecular Theory
2. Electron Theory
3. An electron revolving around the nucleus gives
the atom a magnetic property
4. The electron opening at its own axis becomes
a tiny permanent magnet
Scientists with Important
Contributions to the Field of
Electromagnetism
Hans Christian Oersted
Danish scientist who proved the relationship
between magnetism and electricity
William Gilbert
The scientist who made the earliest investigation to the
discovery of the many properties of natural and
artificial magnets
Andre Marie Ampere
Formulated laws on electromagnetic forces based
on his experiments
Heinrich Friedrich Emil Lenz
Formulated Lenz’s law, for determining the sign
and direction of an induced current or voltage.
Michael Faraday
Discovered electromagnetic induction.
Laws Concerning
Electromagnetism
Lenz’s Law
The direction of an induced current (and hence,
induced voltage) is opposite the direction of
what causes it.
Faraday’s Law
The induced EMF in a coil is proportional to the
product of the number of loops and the rate at
which the magnetic flux changes within the
loops.
Coulomb’s Law of Magnetism
The force between two magnetic poles is
directly proportional to the products of the
strength of the poles and inversely proportional
to the square of the distance between them.
Right Hand Rule
Point the fingers to the
direction of the magnetic
field and the thumb to the
direction of the velocity of
a positive charge. The
palm then points to the
direction of the force on
the charge.
Applications of Electromagnetism
Semiconductors
A substance that
allows only little
current to pass
through.
Insulators
Materials that
resist the flow
of charged
particles.
Superconductors
Materials that
offer zero
resistance to the
flow of electric
current.
Generator
Converts electrical
mechanical energy into
electrical energy.
Commutator – used to produce Armature – also known as
direct current in a generator.
rotor, part which carries the
coil.
Stator – the stationary parts of a
generator.
Dynamo – electromagnet in a
direct current generator.
Alternator- the electromagnet in an
alternating current generator. Produces
polyphase AC.
Transformer
A transformer is an device
that converts voltages
from one magnitude to
another.
Types of Transformers
A step-up transformer
converts to a higher
voltage rating.
A step-down transformer
converts to a lower
voltage rating.
Motor
Converts electrical energy into mechanical energy.
Electromagnetic Induction
The generation of an electromotive force and
current by a changing magnetic field.
Ways of Generating and
Distributing Electric Energy
Power Plant
Any system used to
generate mechanical
or electrical power
plant that can be
utilized to perform
work.
Hydroelectric Power Plants
Converts the energy of falling water from dams into
electric energy.
Geothermal Power Plants
Utilizes energy from the heat beneath the Earth’s
surface to generate electricity,
Solar Power Plants
Harnesses energy that comes from the sun.
Fossil Fuels
Made up of decomposed plant and animal matter
formed many hundreds of millions of years ago.
Forms of Fossil Fuel
•Coal
•Natural Gas
•Oil
Liquefied Petroleum Gas
By-product produced during the oil refining process.
Biodiesel
Agriculture based-product made from vegetable oil
and animal fat.
Process of Charging
1. Conduction – charging by contact between the
neutrals body and the charging body
2. Induction – does not involver contact between
the neutral body and the charging body
Electroscope
Device for determining the kind of charge of a
body
Electric Potential
Scalar quantity equivalent to voltage
Capacitance
Ability of the capacitor to store charges
Different Uses of Magnetism
A. Magnetic Memo Holder
B. Washing Machine
C. Refrigerator
D. Electric Fans
E. Loud Speaker
Uses of Electromagnet
1.
2.
3.
4.
5.
6.
Doorbell
Electric Motor
Generators
Telegraphs
Microphones, Earphones
Lifting heavy pieces of scrap iron
Project in Physics
Presented by:
Mark Oliver Ian C. Delos Reyes
Pia Marie V. Alhambra
Mary Justleene C. Calara
Ma. Angelica T. Castro
Vanessa C. Chua