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It is the ability to do work.Energy is always changing.
We can’t create energy.We can’t destroy energy.We can only transform energy.
EnergyEnergy
Forms of energyForms of energy
Thermal energy
Electrical energy
Kinetic energy
Light energy
Chemical energy
Electrical energyElectrical energyMany thinngs we use everyday work
with electrical energy. Lightnings, during a storm, produce
electrical energy.
Chemical energyChemical energy
It is stored in:
Fuels: Wood Petrol
Gas Coal
Food (living things):
The energy is released when the object
which contains it is burnt.
Light sourceLight sourceIt is anything which emits light.
Natural: It is not created by man.
Artificial: It is created by man.
Properties of lightProperties of light
It moves in a straight line.
It moves in all directions.
It travels very fast.
It interacts with the objects it reaches. Light can be reflected, absorbed or it can pass through the object.
Phenomena of light.Phenomena of light.Shadow: It is the dark area formed behind an opaque
object when it blocks the light.
Composition of light: It is a mixture of 7 different colours, but we
see it as white.
SOUND ENERGYSOUND ENERGYAnything that makes a sound has sound
energy.Sound is produced when objects vibrate.
It travels in waves and in all directions.It also travels very fast but not as fast as
light.
SOUND ENERGYSOUND ENERGYSound can travel through air and water.
Unlike light it can travel through opaque objects.
Like light, sound can reflect off some objects. When this happens we can hear an echo.
Energy sources:Energy sources:
Renewable: It does not run out. It does not cause pollution.
Non-renewable: It will run out. It causes pollution.
The efficient use of energyThe efficient use of energyWe must use less non-renewable energy,
because it pollutes The Earth and it can run out.
We must use more renewable energy, because it does not pollute and it does not run out.
We must save energy by:
◦ Using more efficent motors.
◦ Avoiding unnecessary consumption.
◦ Recycling, reducing and reusing materials. (3 R’s)
◦ Use energy saving light bulbs