Forms of Energy in
everyday technology
All forms of energy used in everyday technology can be grouped
into two main types: potential energy or kinetic energy. Potential
energy is stored energy. Kinetic energy is the energy of movement.
Fireworks transform
potential chemical
energy into three different
forms of kinetic energy
– heat, light and sound
energies.
Forms of potential energy and
kinetic energy
Forms of potential energy include chemical and electrical energies.
Forms of kinetic energy include electrical, heat, light and
sound energies.
Potential energy is stored energy that can make
something work later on. Kinetic energy is the energy
of a moving object. The faster an object
moves or the more mass it has, the more
kinetic energy it has.
Electrical energy
Electrical energy can be potential energy or kinetic energy. It
involves electrical charges. Potential electrical energy can
be carried along wires as kinetic energy to provide power to
electrical appliances.
Heat energy
Heat energy is a form of kinetic energy. It is the movement of the
tiny particles within matter. When matter is heated, its particles
bump into each other and move faster. Heat energy is used to cook
meals. Refrigerators transfer heat energy from food to keep it cool.
Light energy
Try this
Tie a 50-centimetre length of
string to a fork and wind the
other end around one finger.
Put the finger in your ear, lean
forward so the fork hangs
freely and hit the fork with
a pen. The fork will vibrate
and the vibrations will travel
through the string to your ear.
Light energy is a form of kinetic energy. Most of the light energy
on Earth comes from the Sun, but light globes, lasers and fireworks
also produce light energy.
Sound energy
Sound energy is a form of kinetic energy. It travels through matter
as waves when a force causes matter’s particles to vibrate. All
musical instruments use vibrations to produce sound.
All uses of everyday
technology involve the
transfer of energy from one
place to another, and the
transformation of energy from
one form into another.
For example, a drumstick being held up
in the air contains potential energy. As the
drummer hits the drum, potential energy is
transformed into kinetic energy. The higher
the drumstick is held before it hits the
drum, the more kinetic energy it gains
as it falls. When the stick hits the drum,
most of the kinetic energy is transformed
into sound energy.
Chemical energy
Chemical energy is a form of potential
energy. It is stored in the chemical bonds
that hold atoms in matter together. When
groups of atoms are held together, they are
called molecules. The chemical energy stored
in the molecules of fireworks is used to create
colourful explosions.
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A television uses electrical energy to
produce light energy in the form of
pictures on the screen and sound energy
in the form of voices and music.
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forms of energy in everyday technology
Motors transform electrical energy
into kinetic energy
Household technology
Almost every type of everyday technology found in our homes
works by transforming electrical energy into other forms, most
often heat, kinetic and light energies. Even the simple act of
making toast for breakfast relies on several forms of energy.
Try this
How many appliances can you find
around the house that have vents
or holes to let the heat out? If an
appliance is operating, hold your
hand above the vents to feel the
hot air.
Electrical appliances produce
heat energy
When an electrical appliance is connected to a power point and
switched on, electrons are forced to move through thin, metal
wires in a circuit, creating an electric current. As the electrons
move, they bump into the atoms of the wire, making them vibrate.
The more the particles in the wire vibrate, the hotter the wire gets.
As electrical energy transforms into heat energy, the appliance
heats up. If appliances are left switched on for a long time, they
can get very warm. Many appliances contain vents or holes to let
the hot air escape into the surrounding air to stop the appliance
from overheating.
Many household appliances contain electric motors. A simple
electric motor is made up of magnets placed near a coil of copper
wire mounted on an axle. When electrons flow through the coil, a
magnetic force spins the coil and the axle.
The blades of an electric fan, for example, are connected to the
axle of a motor. As the axle turns the blades, electrical energy is
transformed into the kinetic energy of the fan and the moving air.
Hair dryers transform electrical energy
into three other forms
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(1791–1867)
English scientist
Michael Faraday
discovered that
when electricity
flows through a
wire in a magnetic
field, the magnetic
field pushes on the
wire. His discovery
led to the invention
of electric motors
and loudspeakers.
The motor of a hair dryer transforms electrical energy into the
rotating kinetic energy of a fan. The turning fan pushes air across a
wire heating element, which transfers heat energy to the air. The
fan also produces sound energy as it turns.
1. Wires carry electrical
energy from the power
point to the motor.
2. When electricity flows
through the coil, the magnets
force the motor to spin.
magnet
Fans, televisions and
lights are examples
of appliances that are
connected to electric
circuits and transform
electrical energy into
other forms, including
heat energy.
Michael Faraday
Electric motors
transform electrical
energy into other forms of
energy in many appliances,
such as washing machines,
refrigerators, fans and power
tools, such as this drill.
Scientist Snapshot
axle
The element in a hair dryer transforms
electrical energy into heat energy and
transfers heat energy to the air as it
blows across the element.
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household technology
Cooking with heat energy
Keeping food cool by removing
heat energy
Try this
Listen to your refrigerator. Does
the motor run all the time or just
sometimes? When the motor is
running, heat energy is being
transferred from the food inside the
refrigerator to the room it is in. When
the motor is not running, heat energy
is slowly being transferred back to
the food from the room through the
refrigerator’s insulated walls. If you
open the refrigerator door, heat
energy is transferred back in much
more quickly.
A refrigerator is an electrical appliance that keeps food at a low
temperature by removing heat energy from it.
A refrigerator has a closed system of pipes filled with a liquid called
a refrigerant. The pipes carry the refrigerant from the outside of
the refrigerator to the inside and back again. The pipes get wider
where they enter the refrigerator. As the refrigerant enters the
wider pipe, it expands and evaporates. As it evaporates into a
gas, it absorbs heat energy, which cools the food down.
The gas then travels to a motor-driven compressor, which is a
machine that squashes the gas and turns it back into a liquid.
The liquid refrigerant gets hot and travels through a thin pipe at
the back of the refrigerator, where it releases the heat energy it
took from the food into the room.
1. The refrigerant evaporates
inside the blue pipes, turning into
a gas and absorbing heat energy.
Heat energy can be transferred easily through some materials,
called conductors, but is not easily transferred through other
materials, called insulators. When we cook, we use metal pots,
which are conductors, to transfer heat energy from the stove to
our food. To avoid burning ourselves, we use oven mitts and pot
handles, which are insulators, to pick up hot pots and pans.
Conductors
Conductors are usually made of metal. Electrons in metal atoms can
break away and travel through the material, and bump into other
atoms. This allows the heat to travel quickly through the material.
Try this
Bring a small pot of water on the
stove to the boil with the lid on.
Watch and listen as heat energy is
conducted from the stove to the
pot and the water. What do you see
and hear?
Insulators
Insulators are made of non-metal materials. These materials do
not conduct heat energy very well because electrons cannot break
away from their atoms. Oven mitts, for example, are made of
fabrics, such as cotton, which also trap air. The trapped air makes
them better insulators.
This baking tray is
made of metal, which
conducts heat energy to cook
the buns. The oven mitts are
insulators, which slow down the
transfer of heat energy from
the tray to the hands.
2. The refrigerant turns
back into a liquid inside
the orange pipes.
Refrigerators cool food by removing
heat energy from it. This slows down the
action of microscopic living things called
bacteria, which cause food to break down
and rot at warmer temperatures.
compressor
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