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A–Z
SCHOOL J
...
S
DEPARTMENT
OF SCIENCE
FORM TWO
ELECTRICAL
ENERGY

A – Z SCHOOL
THIRD TERM FORM TWO (2)
ELECTRICAL ENERGY
NB; 1
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2
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Learning Objectives
After studying this unit, you should be able to;
• Describe ways of generating electrical energy
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• Demonstrate the flow of current using a simple electrical circuit
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• Explain ways of conserving electrical energy
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Some of the forms of energy are light energy, heat energy, electrical energy and sound energy
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Electrical energy is a form of energy that enables charged particles known as electrons to move by
flowing through a medium that conducts electricity, known as a conductor
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There are two types of electric current; direct current (DC) and alternating
current (AC)
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DEFINITIONS OF SOME BASIC TERMS
• ELECTRICAL ENERGY; is the energy produced as a result of movement of electrons
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• ELECTRIC CURRENT; is the flow of charges (electrons) per second
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• ELECTROMOTIVE FORCE (E
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F); is the source that provides the force necessary to move an
electron to generate electricity
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electrical
energy has sources as well
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Solar panels/solar energy
2
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Hydroelectric power
4
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Fuel cells
6
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Voltaic cells
Let’s consider each of these sources of electrical energy
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Solar cells are devices, which turn the sun’s radiant energy into electricity
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WINDMILLS
A windmill is a machine designed to convert the energy of the wind to either pump water or
produce electricity
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Turbines is a machine for producing continuous power in which a wheel or rotor, typically fitted
with vanes, is made to revolve by a fast-moving flow of water, stream, gas, air, or other fluid
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Hydroelectric dams produces
electrical power through the use of the gravitational force of falling water or flowing water
(kinetic energy)
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The power generated depends on the volume and difference in height
between the source and the water’s outflow
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In Ghana the Akosombo Dam and Kpong Dam generate electricity
for the nation
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Generators may produce direct current (D
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) or alternating current (A
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Direct current occurs
when current flows in the same direction all the time
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g
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A generator consist of wire wound round a metal core
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When the armature rotates in a magnetic field a potential difference is
produced between the ends of the wire
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FUEL CELLS
A fuel cell is a device that coverts the energy of a chemical reaction directly into electrical
energy (electricity)
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These are;
i
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ii
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The two electrodes (anode and cathode) are separated by an electrolyte which is ionic in nature
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Fuel cells are
now being used in some cars to replace fossil fuels (petrol, diesel, etc
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g
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DRY CELLS (BATTERIES)
A cell is a device that stores energy in the form of chemicals, the energy being released when a
conductor is connected between the terminals of cell
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A cell
consist of two different plates, a positive plate and a negative plate
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The plates are called electrodes which
are conductors
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When two or more cells
are connected together, they form a battery
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These are
1
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g
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2
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g
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Meaning it can easily be carried, moved or handled
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It is used to produce electricity in torches, radios and other portable
appliances
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INTERNAL STRUCTURE OF PRIMARY OR DRY CELL
Primary cell has carbon rod and Zinc plate as its electrode
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The top plate (positive plate) is attached to the carbon rod and the
bottom plate is attached to the zinc case (negative plate)
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Since opposite charges attract, electrons in the cell are set into motion to
produce electric current
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The liquid is
mostly an acid (Sulphuric acid - H2SO4)
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They can be recharged by restoring the electrode (acid) and running a small quantity of
current through it
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g
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DIFFERENCE BETWEEN A DRY CELL AND A WET CELL
DRY CELL
1
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Does not last
3
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Contains liquid electrolyte
2
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Can be recharged after its electrical
energy is exhausted

DIFFERENCE BETWEEN A BATTERY AND A FUEL CELL
BATTERY
1
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Requires recharging
3
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Its electrodes reacts and change as
battery runs down or is recharged

FUEL CELL
1
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Does not require recharging
3
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Its electrodes are relatively stable

NB; Voltaic cells; the voltaic cell is the first electric battery, invented by Alessandro Volta in 1800
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In his research, he placed together several pairs of alternating copper and zinc discs
separated by cloth or cardboard and soaked the cloth or cardboard in brine (salt water) to increase
conductivity, and an electric current was produced
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END OF LESSON ONE

Emmanuel Akimi

“The secret to success is to know something nobody else know” – Aristotle Onassis

A – Z SCHOOL/ J
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S Department of Science



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