Lesson Notes By Weeks and Term v4 - JHS 3
CONVERSION AND CONSERVATION OF ENERGY
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CONVERSION AND CONSERVATION OF ENERGY
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Subject: Science
Class: JHS 3
Term: 2nd Term
Week: 11
Grade code: B9.4.3.1.1
Strand code: 4
Sub-strand code: 3
Content standard code: B9.4.3.1
Indicator code: B9.4.3.1.1
Theme: FORCES AND ENERGY
Subtheme: CONVERSION AND CONSERVATION OF ENERGY
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Energy makes things happen: lighting our homes, cooking food, powering phones, moving vehicles, and running machines in Ghanaian homes, farms, and industries. In daily life, energy is changed from one form to another (conversion). At the same time, the total energy does not disappear; it is transferred and transformed (conservation). Understanding conversion and conservation helps learners explain how devices work, why we pay electricity bills, why machines heat up, and how to save energy.
A. What is Energy? Energy is the ability to do work or cause change. Common forms of energy at JHS level: Chemical energy (food, petrol, batteries, charcoal, LPG) Electrical energy (mains electricity, power banks) Light (radiant) energy (sunlight, bulbs) Heat (thermal) energy (fire, hot water, electric iron) Sound energy (speaker, drum) Kinetic energy (moving objects: bicycle, fan blades) Potential energy (stored energy due to position or condition: raised stone, stretched rubber band)
B. Energy Conversion (Transformation) Energy conversion is the process of changing energy from one form to another. Energy conversion chain We can represent conversion using arrows: Input energy → Output energy (useful) + Output energy (wasted)
Important note: In real devices, not all input energy becomes the desired output. Some becomes “wasted” energy, usually heat and sometimes sound. Examples in Ghanaian contexts (with clear chains)
1) Torchlight (battery torch) Chemical energy (battery) → Electrical energy → Light energy + Heat energy (wasted)