Energy: Heat, Light and Sound

Energy is the capacity to do work. It exists in many forms: kinetic (motion), potential (stored), thermal (heat), chemical (bonds), electrical, light, and sound. The Law of Conservation of Energy states that energy cannot be created or destroyed — only converted from one form to another. In ecosystems, energy flows from the sun through producers (plants) to consumers. Photosynthesis converts solar energy to chemical energy (glucose). At each trophic level, approximately 10% of energy is transferred to the next level; 90% is lost as heat (respiration, waste). This explains why food chains are short and why pyramids of biomass narrow from producers upward. Efficiency = useful energy output ÷ total energy input × 100%. Power stations, engines, and living organisms all face energy losses. Renewable energy sources (solar, wind, hydro) and non-renewable sources (fossil fuels, nuclear) have different environmental impacts.