CHAPTER 5: ENERGY – SCIENCE STANDARD FOUR NOTES
Demonstrate a basic understanding of types of energy and their uses
Describe types of energy
Recognizing various types of energy and their uses
Concept of energy
What is energy?
Energy is the ability of doing work.
The standard unit of energy is Joule (J)
Types of energy
There are two types of energy
- Potential energy
- Kinetic energy
Potential energy
What is potential energy?
Potential energy is the energy possessed by a body due to its position (height).
Example of potential energy
- A bucket contain water
Kinetic energy
What is kinetic energy?
Kinetic energy is the energy possessed by a body due to its motion.
Example of kinetic energy
- Moving water in a river
Activity showing potential and kinetic energy
A good example is a swing.
- When it is on its way up, it is using kinetic energy since the energy is in motion. When it reaches the top it has potential (or stored) energy. When it goes down it is using kinetic energy again.
Form of energy
There are various forms of energy
- Heat (thermal)
- Light (radiant)
- Motion (kinetic)
- Electrical
- Chemical
- Nuclear energy
- Gravitational
- Sound energy
EXERCISE
- What is energy?
- Outline two types of energy
- _____________________
- _____________________
- Mention five forms of energy
- _____________________
- _____________________
- _____________________
- _____________________
- _____________________
- To see an object, there must be __________________
- __________________is the energy possessed by the body when it is in motion.
- __________________is the energy possessed by the body due to its position.
Light energy
Light energy is the form of energy which helps us to see
Sources of light energy
There are two sources of light energy which are
- Natural source of light
- Artificial source of light
NOTE
Natural sources of light are the sources of light that emit their own light.
Artificial sources of light are sources of light that cannot emit their own light.
Sound energy
Sound energy is the form of energy produced by vibration. Sound energy travels in all directions.
Sources of energy
- Natural sources of sound
- Artificial sources of sound (Man-made sources of sound)
- Examples of natural sources of sound
Examples of artificial sources of sound
Sources of energy
There are two main sources of energy
- Renewable energy
- Non – renewable energy
Renewable sources of energy
Renewable energy sources are the sources of energy that cannot be exhausted or replenished.
Examples of renewable energy source:-
- Solar energy from the sun
- Geothermal energy from heat inside the earth.
- Wind energy
- Biomass from plants
- Hydropower from flowing water
Non-renewable energy sources
Non-renewable energy sources are source of energy that can be exhausted or replenished.
Examples of non-renewable energy sources are:-
- Crude oil
- Natural gas
- Coal
- Uranium (nuclear energy)
Uses of energy
- It is used by plant to make their own food (light)
- It is used for cooking (Heat)
- It is used for drying crops and clothes (heat)
- It is used for giving instructions (sound)
- It is used in compass to show direction (magnetic)
- It is used to operate various machines
(a) Identify sources of the electrical energy
(i) Meaning of electrical energy
What is electrical energy?
Electrical energy is a form of energy produced by electricity.
Electricity is a flowing of electrons through a conductor such as wire.
Types of electricity
There are two types of electricity
- Static electricity
- Current electricity
Static electricity
What is static electricity?
Static electricity is a type of electricity produced when a surface is rubbed into another surface.
Example: When a plastic ruler is rubbed in the hair, it attracts small pieces of paper.
Current electricity
What is current electricity?
Current electricity is an electric charge in motion.
Types of current electricity
- Direct current (Dc- current)
- Alternating current (Ac-current)
(ii) Sources of electrical energy
The following are sources of current electricity:-
- Dry cells
- Wet cells or battery
- Waterfalls
- Geothermal power
- Solar energy
- Petrol and diesel generators
- Wind driven turbines
- Bicycle dynamos
Solar panel
Dry cells (Battery)
Bicycle dynamo
Generator
Waterfalls
(iii) Uses of electrical energy
- It is used for lighting
- It is used for heating
- We use electrical cookers for cooking and heating food materials.
- It is used for communication
- Some means of communication use electricity to give us important information such as TV and radio.
- It is used for computers
- It is used for transportation
- It is used for operating machines; some engines cannot operate without electrical energy
Power plant
(iv) Performing experiments which indicate the presence of electrical energy
- Materials
- Plastic ruler
- Piece of paper
- Hair
Procedures
- To guide pupils to arrange materials need in the experiments.
- To guide pupils to take plastic ruler and rub onto the hair for about 1-2 minutes.
- To guide pupils to take a rubbed plastic ruler and place near to the piece of paper.
- To guide pupils to observe what will happen in step number 3.
Results
A small piece of paper will be attracted by a rubbed plastic ruler. This indicates the presence of electrical energy.
Plastic ruler
Piece of paper
Hair
EXERCISE
Choose the correct answer
1. ___________ is the ability of doing work.
(a) Power (b) Work (c) Force (d) Energy ( )
2. The main two types of energy are _________
(a) Chemical and mechanical (b) Potential and kinetic (c) Natural and artificial (d) None of the above ( )
3. Type of energy possessed by the body due to its position called _______
(a) Potential (b) Kinetic (c) Radiation (d) Electrical ( )
4. The SI unit of energy is __________
(a) Joule (J) (b) Newton (c) Meter per second (d) Nitrogen ( )
5. The source of energy that can be exhausted is called _____________
(a) Renewable (b) Non-renewable (c) Non-revisable (d) Static ( )
