Download Electrical Energy Production

Electrical
Potential Energy
and Voltage
Grade 9 Science
• Electrochemical Cells convert
chemical energy to electrical
energy.
• A Battery is another name for an
electrochemical cell, or
sometimes several cells joined
together.
Energy is the ability to do work.
• Any moving object has Potential energy.
• Kinetic energy is the energy stored in an
object.
• The energy stored in a
battery is called Electric
Potential Energy, since
the electrons have the
ability to do work once
they leave the battery. In
order for the electrons to
release their stored
energy, the battery must
be hooked up to a device.
Electric Potential Difference
• Remember that charge is measured in
Coulombs.
• A Volt (V) is defined as the amount of
electric potential energy per one coulomb of
charge.
Producing Voltage
• Batteries can be classified into two groups:
Dry cells and Wet cells. Dry cells are found in
devices like flashlights. Wet cells are found in
cars and
motorcycles.
• A battery has two terminals called Electrodes.
The electrodes are usually made of two
different metals, but can be made of other
substances.
• The electrodes are in an electrolyte, which is a
substance that is able to conduct electricity.
• The amount of voltage that is produced by an
electrochemical cell depends on the metals
and electrolyte used.
Other Sources of Energy
• Friction (rubbing 2
objects together to
produce a charge)
• Piezoelectric crystals
(when crystals such as
quartz are hit or
squeezed, they produce
a burst of electricity –
BBQ lighter)
Other Sources of Energy
• Photo-electrochemical
cells (solar cells)
• Thermocouples (a loop of
two wires made of
different metals that
produces electricity when
heated or cooled)
Other Sources of Energy
• Generators (consist of a magnet that is able
to generate electricity when it is moving next
to a wire. The magnet may be moved using
water (hydroelectric) or steam from a nuclear
plant.)
Electrical Current
Grade 9 Science
• A complete pathway that allows Electrons to
flow is called an electric circuit
• Any device that transforms electrical energy
into another form of energy is called an
electric load (ex. heat energy, light energy,
sound energy)
For example:
• A toaster is an electric load that transforms
electrical energy into heat energy.
• A radio is an electric load that transforms
electrical energy into sound energy.
Circuit Components and Diagrams
• All circuits are made up of four basic types of
parts:
– Source - The source of electrical energy (ex: a
battery).
– Conductor - The wire through which electricity
flows.
– Load - A device that transforms electrical energy
into another type of energy (ex: a light bulb)
– Switch - For turning the circuit on and off by
making or closing a break in the circuit.
• Circuit diagrams use symbols to show
different components in the circuit.
• These are the symbols most commonly used
in circuit diagrams:
A circuit diagram (right) representing an actual
circuit (left).
• When an electrical current travels through a
circuit, electrons are pushed from the
negative terminal of the battery, through the
circuit, and back to the positive terminal of
the battery.
• The conducting wire (or metal wire), already
contains electrons throughout its length, so
as soon as the electrons start pushing from
the negative terminal of the battery, the
current flow starts.
• The continuous flow of electrons in a
complete circuit is called current electricity.
Conventional Current
• In 1747, Benjamin Franklin introduced
the idea that positively charged objects
were bigger than negatively charged
particles
• He suggested that electricity flows
positive to negative
• The concept of electron flow to
describe current was not accepted until
1800 after electrons were discovered
Current: The Measure of Flow
• Electric current is defined as the amount of
charge passing a point in a conductor every
second. Electric current is measured in
amperes (A). An ammeter is a device to
measure current in units of amperes. Its
symbol on a circuit diagram looks like:
How do we meet our
electrical energy
demands?
What does this image show?
The Flow of Electrons
• Unlike static electricity, current electricity
involves the FLOW of electrons.
• Electrons flow through a conductor in a
controlled way.
• The steady continuous flow of electrons
means that the flow can be used to do work.
• Static discharge is unpredictable and random.
Electricity Song
(to the tune of Frere a Jacque)
Electricity
Electricity
Controlled flow of electrons
Controlled flow of electrons
Your negative flows towards positive
Conductors allow electrons to flow along
What’s our source of electrons?
What’s our source of electrons?
We use hydro
Flowing water through a dam
Produces electron flow
Flow through our town
We connect appliances
To our walls and that connects
Allowing electrons to flow
Allowing electrons to flow
Conductors and Insulators
• Conductors are materials that allow the flow
of electrons to move easily through them
• Insulators do not allow electrons to flow
through them
• Semiconductors are materials that allow
electrons to flow through them under certain
conditions.
Conductors
Metals
Gold
Copper
Aluminum
Salt water
Non conductors
Non metals
Plastic
Rubber
Paper
Styrofoam
What do you
know about
attraction of
charged
particles?
Summary:
1. Current electricity involves the controlled
flow of electrons through a conductor.
2. Current electricity moves easily though a
conductor and poorly through an insulator.
3. Current electricity requires a source of
electrical energy to create a flow of electrons.
Assignment
Video of the following:
1. Different between potential and
kinetic energy
2. Direction of electron flow
3. Show your definition of current