IGCSE
PHYSICS
0625 / 0654
By ANKIT SHARMA
SYLLABUS
0625 0654
Energy Energy comes from Greek
word Energia which means “
being at work”.
It's the property which is
transferred to an object to
perform work on or heat up
the object.
Energy is measure in terms of
Joules(J)
Energy stores
• Energy is stored in in
objects in their different
energy stores.
Chemical
Kinetic Store store(energy is
Energy
(moving objects stored in bonds
have energy in their between atoms and
Kinetic Store) molecules)
stores Electrostatic
Nuclear store (charged objects
Gravitational
(energy is stored interacting with
(When you lift
inside the each other have
objects , energy is
nucleus released energy in
gained in
during Fission electrostatic store)
gravitational store)
and Fusion)
Internal(thermal)
Elastic Store
energy(objects
(objects when they
are hot or cold
are squashed, bent
depending on
or stretched gain
amount of energy
energy in elastic
in their internal
store)
store)
This Photo by Unknown Author is licensed under CC BY
Mechanical Work Done –
How Energy Transferring energy by applying a
Transfers between force or by doing work
Stores Examples: Push/ Pull / Kick
Electricity
or Electric
Workdone
Motors, heaters, speakers,
LEDs etc. (transfers energy
from one store to other)
This Photo by Unknown Author is licensed under CC BY-SA-NC
Transfer as Electromagnetic
Radiation: In electromagnetic waves,
energy is transferred through vibrations of
electric and magnetic fields.
Roughly 49% of solar radiation is
infrared between 700nm-1mm; about
7% is from ultra-violet between 100-
400mm; less than 1% of solar radiation
is emitted as x-rays, gamma rays and
radio waves.
Waves
Transfer of transfer
energy as energy but
not mass
SOUND
Sound waves are Longitudinal waves. In
sound waves, energy is transferred
through vibration of air particles or
particles of a solid through which the
sound travels.
Water
Waves
In water waves,
energy is
transferred through
the vibration of the
water particles.
Heating
chemical energy in fuels
is transferred to internal
energy of water via heat
transfer.
This Photo by Unknown Author is licensed under CC BY
Principle of conservation
of energy
• Energy can neither be created nor
destroyed, it can only be transferred from
one store to another.
• For a closed system total amount of
energy remains constant
• The total amount of energy transferred
into the system must be equal to the total
amount of energy transferred away from
the system.
Examples of energy conversion.
Example 1: Hitting a ball with a bat
Example 2 Boiling water
in a kettle
• Electric energy from mains supply is
transferred to thermal store of heating
element of kettle
• Heating element gets hotter and energy is
transferred via heat to thermal store of
water and some to thermal store of
kettle(wasted).
• Energy in thermal store of water raises its
temperature.
Energy Flow Energy stores and transfers can be represented
Diagrams by energy flow diagrams.
Kinetic Energy- Describing
and Calculating
Kinetic energy is the energy of motion and is possessed
by an object due to its motion. The amount of kinetic
energy an object has is dependent on its mass and
speed. The SI unit of kinetic energy is the joule
1
Ek = 𝑚𝑣 2
2
m = mass of the object
V = speed/ velocity of the object
Problems
Q-Calculate KE of ball of mass 2 Q- A bullet of mass 0.02 kg was
kg moving with speed of 2 m/s. shot from a gun , the energy in it
kinetic store is 2000 J. What is
the speed of the bullet?
Gravitational
Potential
Energy-
Describing and
Calculating
The energy possessed by an
object due to its height in
gravitational field.
ΔEp = mgΔh
Unit is Joules(J)
Sankey
Diagrams
• Sankey Diagrams are
used to represent energy
transfers using arrows.
• The size of an arrow
shows proportion of
energy transfer to that
store
Total energy = Useful
energy + wasted energy
Syllabus- 0625/0654
Energy, work and power
WORK
Work or Workdone
Workdone on an object is the amount of energy
transferred as Kinetic Energy(into kinetic store) or
potential energy(potential store) to an object.
W = F X d= ΔE
Unit: Newton meter (Nm) or Joules (J)
1.7.3 Energy resources
0625 0654
How is electricity
generated
THERMAL
POWER
PLANT
Chemical energy(in
fossil fuel)
converted into
Electricity
Biofuel to
electric energy
A biofuel is any liquid fuel
derived from biological
material such as trees,
agricultural wastes, crops, or
grass.
Since late 1800 biofuels was
in use for cooking and in
lamps.
Tidal energy
• https://www.youtube.com/watch?
v=VkTRcTyDSyk
Hydroelectric energy
Converts potential energy stored in
water which is stored in a dam.
to electricity.
Geothermal
Energy-Heat from
the earths core is used to
convert water into steam
and then steam is used to
move turbine
Elements like Uranium Plutonium
and Thorium undergo splitting of
nucleus fission reaction to produce
Nuclear Fuel large amount of energy.
Solar cells
• Solar cells are made of Si and Ge.
• They convert solar energy into
electricity.
• Also we have devices like solar water
heater which directly utilizes solar
energy to heat water.
Wind Energy- A byproduct of
solar energy
