1. Is there an Ultimate Energy Source?

2. Is there an ultimate energy source?
The grass gets its energy from the Sun via photosynthesis.
The Sun is the ultimate energy source
The lamb gets its energy by eating the grass ….
…. and WE get our energy by eating the lamb!

3. Forms of Energy

4. Gravitational Potential Energy
This is energy when something is ‘out of position’. This rock climber has potential energy. The further she climbs – the more potential energy she would gain.
Water held behind a dam has this type of energy too.

5. Chemical Potential Energy
When a fuel burns, its energy is released by chemical reactions. The energy stored in the fuel is called chemical potential energy (or chemical energy for short). Batteries also store chemical potential energy.

6. Kinetic Energy This is energy due to motion.
All moving objects have kinetic energy
The faster they move (or the more mass they have) the more kinetic energy they have

7. Elastic Potential Energy
A stretched rubber band can do work when released. It has elastic potential energy

8. Electrical Energy
In circuits, the current is a flow of tiny charged particles called electrons. Electrons can transfer energy, for example from a circuit to a hairdryer. They have electrical energy.

9. Nuclear Energy
An atom has a nucleus at its centre. This is made up of particles, held by strong forces. In some atoms the particles become rearranged or the nucleus splits and energy is released.

10. Thermal Energy
When hot objects cool down, their atoms and molecules slow down and lose energy. This is known as thermal energy or heat.

11. Radiated Energy
Examples of this are light from a lamp and radio signals from a transmitter.

12. Sound
Anything that makes a noise has this form of energy. For example air compressions from a loudspeaker or other sound source.

13. Energy Transfers

14. What is the energy conversion in each of the solar cells?
Electrical Energy
Light (radiated)

15. What are the energy transfers in this match?
Chemical Energy
Light & Heat
Sound is wasted

16. What energy conversions happen in a windmill?
Kinetic Energy
Electrical Energy

17. What is the unit for ENERGY?
The Unit for all forms of energy is the Joule (J).
The unit is named after the scientist in the picture.
1 kJ = 1,000J
1 MJ = 1,000,000J

18. Conservation of Energy & Efficiency

19. What is the Principle of ‘Conservation of Energy’?
ENERGY can never be CREATED or DESTROYED – it can only be CONVERTED from one form to another.
Another important principle is:
Energy is ONLY USEFUL when it is CONVERTED from one form to another.

20. ‘Energy cannot be created or destroyed, but it can be changed from one form to another’
Chemical Energy
Light (radiated) Energy
wanted
Heat (thermal) Energy
wasted
The wasted Heat Energy now heats up the surroundings. It is NEVER destroyed!

21. Are energy conversions 100% efficient?
NO device is 100% efficient and the wasted energy is dissipated usually as HEAT & SOUND
Think of this washing machine. It gets noisy and hot when it is switched on to wash our clothes

22. Efficiency can be expressed as a fraction, decimal or percentage
What is EFFICIENCY?
The efficiency of any device is defined as:
Useful energy OUTPUT
Efficiency =
Useful energy INPUT
Energy out
Efficiency can be expressed as a fraction, decimal or percentage
Efficiency x Energy In

23. Calculate the efficiency of this computer
1200J of electrical energy is supplied to the computer. 200J of energy are wasted in the form of heat & sound.
Efficiency = Energy output
Energy Input
= 1,000 / 1,200
= (or 83%)