Edexcel International GCSE Physics Section 4: Energy Resources and Energy Transfers Exam Questions

About Edexcel International GCSE Physics Section 4: Energy Resources and Energy Transfers

Section 4 of Edexcel International GCSE Physics brings together energy transfers, work and power, and how electricity is generated. You need to describe energy stores and transfers, apply conservation of energy, calculate efficiency and draw Sankey diagrams. The section covers heat transfer by conduction, convection and radiation and how these are reduced in houses and vacuum flasks. You then calculate work done, gravitational potential energy, kinetic energy and power. The final part compares renewable and non-renewable energy resources used to generate electricity. It builds on forces in Section 1 and links to generators in Section 6. Examiners commonly set GPE to KE calculations and explanations of heat transfer.

What you need to know

• Energy stores and transfers Stores include chemical, kinetic, gravitational, elastic, thermal, magnetic, electrostatic and nuclear. Energy is transferred mechanically, electrically, by heating and by radiation, and is always conserved.
• Efficiency and Sankey diagrams Efficiency = useful energy output / total energy input x 100%. Sankey diagrams show input, useful output and wasted energy with arrow widths drawn to scale.
• Conduction, convection, radiation Conduction transfers energy through solids by vibrating particles (and free electrons in metals). Convection occurs in fluids as warmer, less dense fluid rises. Radiation is infrared and needs no medium; dark, matt surfaces are good absorbers and emitters.
• Reducing heat loss Insulation such as loft insulation, cavity wall insulation and double glazing trap air, a poor conductor, reducing conduction and convection.
• Work and power Work done = force x distance moved (W = Fd) and equals energy transferred. Power = work done / time taken (P = W / t).
• GPE and KE GPE = mgh and KE = 1/2 mv^2. Use conservation of energy to link them for falling or swinging objects.
• Energy resources Electricity can be generated from fossil fuels, nuclear, wind, water (waves, tides, hydroelectric), geothermal and solar. Compare them by reliability, cost, renewability and environmental impact.

Common mistakes in Section 4: Energy Resources and Energy Transfers

• Saying heat rises. Hot fluid rises because it is less dense than the surrounding fluid.
• Saying air is a good insulator because it is cold. Air is a poor conductor, and trapping it stops convection currents.
• Forgetting that radiation does not need a medium. Infrared radiation can travel through a vacuum.
• Forgetting to square velocity in KE = 1/2 mv^2.
• Calling nuclear power renewable. It uses uranium, which is a finite resource.

Try three Section 4: Energy Resources and Energy Transfers exam-style questions