Question 1: Define renewable energy sources and explain why they are considered sustainable.

Answer: Renewable energy sources are natural sources that can be replenished naturally within a human lifespan, such as sunlight, wind, and water. They are considered sustainable because they do not deplete over time and have minimal environmental impact.

Question 2: List four common types of renewable energy sources.

Answer: Solar energy, wind energy, hydroelectric (water) energy, geothermal energy.

Question 1: Describe how a solar panel converts sunlight into electrical energy.

Answer: A solar panel contains photovoltaic cells that absorb sunlight, exciting electrons and creating an electric current, which can then be used as electrical power.

Question 2: Explain the principle behind wind turbines generating electricity.

Answer: Wind turbines use the kinetic energy of moving air to rotate blades connected to a generator, which converts mechanical energy into electrical energy.

Question 1: A solar panel receives 800 W/m² of sunlight and has an area of 2 m². If the efficiency of the panel is 15%, calculate the electrical power output in watts.

Answer: Power input = Solar irradiance × Area = 800 W/m² × 2 m² = 1600 W; Power output = Efficiency × Power input = 0.15 × 1600 W = 240 W.

Question 2: If a wind turbine has a swept area of 50 m² and the wind speed is 10 m/s, estimate the kinetic energy flux in watts (use air density = 1.225 kg/m³).

Answer: Kinetic energy flux = 0.5 × air density × area × wind speed³ = 0.5 × 1.225 kg/m³ × 50 m² × (10 m/s)³ = 0.5 × 1.225 × 50 × 1000 = 30,625 W.

Question 1: Identify two safety precautions that should be considered when installing or maintaining wind turbines.

Answer: Ensuring proper electrical grounding to prevent shocks and maintaining safe distances from moving blades to avoid injury.

Question 2: Describe an experiment to demonstrate the greenhouse effect related to solar energy.

Answer: One possible experiment involves placing two identical containers, one covered with clear plastic (to simulate a greenhouse) and the other uncovered, both exposed to sunlight. Measure the temperature inside each container over time. The container with plastic should show a higher temperature, demonstrating how greenhouse gases trap heat.

Question 1: A hydroelectric dam generates an average power of 500 MW. If the dam operates continuously for 24 hours, how much energy in megawatt-hours (MWh) is produced?

Answer: Energy = Power × Time = 500 MW × 24 hours = 12,000 MWh.

Question 2: Explain how the use of renewable energy sources can impact environmental pollution and climate change.

Answer: Renewable energy sources produce little to no greenhouse gases during operation, reducing pollution and helping to mitigate climate change. Their sustainable nature means they do not deplete natural resources or emit harmful pollutants, leading to cleaner air and a healthier environment.