ELECTROMAGNETIC
INDUCTION
LESSON 2
Unscramble each of the clue words.
1. TEIGACMN LUFX
2. ECGIANTM DELFI
3. DEUSOPLEAKR
4. CETILCER TORMO
5. HDRA CSDIS
PRINCIPLES OF ELECTROMAGNETIC INDUCTION
Faraday's Experiment
 Michael Faraday showed that electricity can be obtianed from
magnetism
The current produced in this way is called an induced current
The process by which the current is obtained is called
electromagnetic induction
To Demonstrate Electromagnetic Induction
The North Pole of the magnet is moved into the coil of the wire
 When a magnet is
plunged into the coil,
the galvanometer
pointer gave a
momentary
deflection
The North pole of the magnet is moved out of the coil of the wire
 Moving out the
magnet out form the
coil, the galvanometer
gave another
deflection
The magnet is held stationary inside the coil of the wire
 No current was
induced if the
magnet was
allowed to
remain at rest
inside or outside
the coil .
• Whenever ther was a relative movement between
magnet and coil, there was induce current.
• The current was induced in the circuit as a result of
the wire being cut by magnetic flux lines when either
the magnet or coil moved.
• An electromotive force is induced whenever there is a
changing magnetic flux in a circuit.
Factors affecting the magnitude of the induced
E.M.F
 Faraday's law of electromagnetic induction states that the
magnitude of the induced e.m.f is proportional to hte rate of change
of the magnetic flux linked with the circuit or rate at which the
magnetic flux are cut.
Faraday also found that the magnitude of the induced current
increases when
 The magnet is moved at a faster speed in and out of the coil.
 A stronger magnet is used.
 The number of turns in the coil is increased
Direction of the Induced E.m.f
 Lenz's law of electromagnetic induction states that the induced
current is always in a direction to oppose the change producing it.
By Lenz's Law
and the RightHand Grip Rule
trace the
direction of
current through
the load resistor
APPLICATION OF MAGNETIC FIELD FORCE
 Loudspeaker
 a very common equipment that
comes in different sizes
 speakers work using gthe
principle of electromagnetic
induction to produce sound waves
 a speaker works throught the
interplay of these three major
components.
 Basic components of the speaker
 cone
 electromagnet
 permanent magnet
APPLICATION OF MAGNETIC FIELD FORCE
 Electric Motor
a device that concerts electrical energy to mechanical energy by applyinf the
principle of electromagnetic induction
A simple motor is composed of




an armature (the rotating coil)
a permanent magnet (source of the magnetic field )
brushes that carry the current to the commutator
a commutator (reverses the current)
 A generator works
in reverse ,
because the
generator uses
mechanical energy
to produce
electrical energy.
How an electric motor works
APPLICATION OF MAGNETIC FIELD FORCE
 Hard Discs
Hard drives are devices used to store information
 First hard drive was developed by the International Business Machines( IBM)
Corporation in 1953
 The drive sotres information using magnetism.
 A drive needs these basic parts to store information :
 magnetic discor platter to store the information
 a spindle to rotate the magnetic discs
 read/write heads that add data or informaion in the platters
A hard disc
ELECTROMAGNETIC INDUCTION
IN POWER GENERATION
LESSON 3
GENERATORS
• Electric generator is a device that converts mechanical energy to
electrical energy through electromagnetic induction.
Parts :

shaft - connected to the motor of the propellers responsible for
the mechanical input
 stator- stationary magnetic field with copper windings
 armature - spins the stator to create eelectromagnetic induction
 commutator - collects electricity and sends it to the brushes
 brushes - which in turn send the current outside
Direct Current(DC ) generator
• It is a type of generator that
converts mechanical energy into
DC electrical energy. It is also
called a dynamo. It generates
pulsating Direct current that
does not change its direction.
Alternating Current (AC) generators
• a generator that converts
mechanical energy into
AC electrical energy. It is
a type of generator
designed to generate
alternating current with a
frequency of 50 or 60 Hz.
HYDROELECTRIC POWER PLANTS
• Power plants - industrialt facilities that generate electricity using
electric generators
- have several types depending on the source :
- geothermal
- nuclear
- coal
- solar
- hydroelectric power plants
 Hydroelectric power plant
- power plant that uses the gravitational potential energy of falling
water to generate electricity
Different types :
-storage hydropower
- run-of-river hydropower
- pumped storage hydropower
- offshore hydropower
Storage hydropower
 Most common power plants which uses dam or a reservoir to store water.
Releasing the water produces electrical energy
Run-of - river hydropower
 Channels water from a river through a canal. The water is used to run a
turbine to generate electricity
Pumped storage hydropower
 A hydropower that harnesses water, which is cycled between the lower and upper
reservoirs through pumps.
• Hydropower plants can be classified into three based
on the energy produced.
1. Large hydropower plants can produce power of
about 30 MW
2. Small hydropower plants porduce 10 MW or less
3. Microhydropower plants produce 1000 kW of
electrical power