(a) Energy Transformations
i. Energy from the sun is used to generate electricity for lighting a house:
- Solar Energy to Electrical Energy: Solar panels capture sunlight (solar energy) and convert it into electrical energy through the photovoltaic effect.
- Electrical Energy to Light Energy: The electrical energy generated is transmitted to light bulbs, where it is transformed into light energy to illuminate the house.
ii. Mechanical energy from the waterfalls is used to generate electricity:
- Potential Energy to Kinetic Energy: Water stored at height in the waterfall has potential energy, which converts into kinetic energy as it flows downward.
- Kinetic Energy to Mechanical Energy: The kinetic energy of falling water turns the blades of a turbine, converting it into mechanical energy.
- Mechanical Energy to Electrical Energy: The turbine, connected to a generator, converts the mechanical energy into electrical energy, which can be used for various applications.
iii. A bicycle wheel is used to turn a dynamo. The electric energy from the dynamo is used to light and power a bulb to produce light:
- Mechanical Energy (from pedaling): When the bicycle wheel is pedaled, you supply mechanical energy by the motion of the bike.
- Mechanical Energy to Electrical Energy: The motion of the bicycle wheel turns the dynamo, which converts mechanical energy into electrical energy.
- Electrical Energy to Light Energy: The electrical energy produced by the dynamo powers the bulb, converting the electricity into light energy.
(b) Reasons for Preferring Gas over Charcoal in Cooking
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Efficiency and Control: Gas burns more efficiently than charcoal and provides better control over heat levels for cooking. This allows for precision when it comes to preparing different dishes.
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Cleanliness: Cooking with gas produces less soot and ash compared to charcoal. This means less cleanup after cooking and a cleaner cooking environment overall.
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Convenience: Gas stoves ignite quickly, offering immediate heat at the turn of a knob without the need for kindling and waiting for coals to become hot as with charcoal.
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Health Considerations: Gas cooking generally produces fewer harmful emissions compared to burning charcoal, potentially resulting in better indoor air quality and health safety.
(4) (a) Definitions
i. Fuel: Fuel is a substance that can be burned or otherwise consumed to produce energy or heat. It can be in various forms, such as solids (like wood or coal), liquids (like gasoline or diesel), or gases (like natural gas or propane), and is used for powering engines, heating, and cooking.
ii. Destructive Distillation of Coal: Destructive distillation of coal is a process where coal is heated in the absence of air (oxygen) to break it down chemically. This process produces several valuable byproducts, including coke (used in steelmaking), coal tar (used in making chemicals), and coal gas (used as a fuel). The process effectively converts solid coal into gaseous, liquid, and solid forms of useful materials.
(b) Factors to Consider in Proposing a Good Fuel for the School Kitchen
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Availability: The fuel should be readily available and accessible in the local area to minimize transportation costs and ensure a steady supply.
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Cost-Effectiveness: The price of the fuel should be within the school budget, ensuring that it is affordable to use regularly without straining financial resources.
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Efficiency: The fuel should have a high energy output for a given amount, allowing for effective cooking with reduced cooking time and less fuel consumption.
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Environmental Impact: The proposed fuel should have minimal negative effects on the environment, such as lower emissions of greenhouse gases and pollutants, contributing to a cleaner and healthier environment.
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