Methods of producing electricity. In this
learning activity you'll review the six
different ways in which electricity is
produced: chemical, friction, heat, light,
magnetism, and pressure. let's click on
the pictures below for a detailed
description of each method. chemical:
metals inserted into chemicals cause a
reaction that transfers electrons to
produce an electrical charge. batteries
operate this way. the chemical is called
an electrolyte. an example of an
electrolyte is one that combines
hydrochloric acid with water. when copper
is inserted into the electrolyte as
shown here electrons transfer from the
metal into the solution. since copper
loses electrons it has a positive charge.
when zinc is inserted into the
electrolyte electrons transfer from the
solution to the metal. since zinc gains
electrons it becomes negatively charged.
one end of the copper bar is the
positive terminal and on one end of the zinc
bar is the negative terminal of the
battery. friction static charges are
probably the best example of producing
electricity by friction. a static charge
occurs when certain materials are rubbed
together and electrons are transferred
from one object to another. the materials
used to produce the charge determine the
type of charge that develops when a
rubber rod is rubbed by a wool cloth.
electrons are removed from the wool and
deposited on the rod the rod becomes
negatively charged because it has an
excess of electrons. if a glass rod is
rubbed by the wall electrons are removed
from the glass and deposited on the wall
the rod becomes positively charged
because it has a deficiency of electrons.
a static electricity charge can only be
built up on insulator materials because
they keep electrons stationary and do
not allow them to move to a different
location.
heat: some materials readily give up
electrons and some materials accept
electrons. copper and zinc are examples
of metals that have this property. when
they are joined together electrons will
leave the copper atom and enter the zinc
atoms therefore the copper becomes
positively charged since it has a
deficiency of electrons and the zinc
becomes negatively charged because it
has a surplus of electrons. the charge
across both metals is proportional to
the temperature to which they are
exposed. as the temperature is increased
more energy is provided to release more
electrons and create a higher voltage. a
practical example of this type of device
is the thermal couple it is used to
measure temperature its voltage is
applied to a voltmeter that has a scale
which reads temperature instead of
voltage.
light:  a light beam consists of particles
called photons when the photons strike
the surface of a plate made from some
materials such as potassium sodium or
lithium electrons from their atoms are
released the electrons traveled to an
adjacent plates made of some other type
of material the material that loses
electrons becomes positively charged and the material that gains electrons
becomes negatively charged. terminals are connected to these plates as shown here.
to provide a voltage to external devices
that use DC electrical power this method
of light activated power is called the
photovoltaic process.
magnetism: when a conductor such as a
copper coil is moved through a magnetic
field created by a magnet the force from
the flux lines of the magnet cause
valence electrons to be dislodged from
the copper atoms. the direction that the
electrons move through the wire is
determined by the direction that the
coil moves relative to the magnet.
electricity that is produced by
generators uses this method.
pressure:  when pressure is applied to
some types of materials such as a
crystal the force of that pressure
causes the electrons to be dislodged
from some of its atoms. the diagram here
shows a crystal before pressure is
applied the material has no charge. as
the right pressure is applied it causes
the electrons to leave one side of the
material and accumulate on the other
side thus positive and negative charges are
built up on opposite sides then the
pressure is released. the electrons
return to their orbits and the material
becomes uncharged. the size of the charge
is proportional to the pressure applied
the name given to the effective pressure
causing electric charges is
piezoelectricity. the word Paizo is
derived from the Greek word meaning
pressure. Paizo crystals have been used
for phonograph pick up. as the needle
rides through the grooves of the record
the crystal bends and produces a varying
voltage that is amplified as it drives a
speaker.
this concludes this learning activity
methods of producing electricity
