Pearson Edexcel International GCSE Science Single Award 13: Physics: Energy resources and energy transfers

Topic 4 follows energy through stores and pathways, then quantifies work, mechanical energy and power. These notes follow Pearson 4SS0 Issue 4. Heating mechanisms, insulation investigations and electricity generation are assigned to broader routes and are excluded.

Energy stores and transfers

Required energy stores are chemical, kinetic, gravitational, elastic, thermal, magnetic, electrostatic and nuclear. Energy transfers mechanically, electrically, by heating, or by radiation such as light and sound.

A battery-powered lamp begins with the battery's chemical store. Energy transfers electrically to the lamp, then by light to the surroundings and by heating to the lamp and air. “Light energy” is best described as a transfer pathway, not a store left inside the lamp.

Energy is conserved: it cannot be created or destroyed. In real devices, energy becomes less useful because it spreads into thermal stores of the surroundings. This does not violate conservation.

Efficiency and Sankey diagrams

Efficiency compares useful output with total output:

$$\text{efficiency}= \frac{\text{useful energy output}} {\text{total energy output}}\times100$$