Energy Transfer Learning Module

📚 Module Overview & Key Units

🎯 Learning Outcomes

4.1 Use the following units: kilogram (kg), joule (J), metre (m), metre/second (m/s), metre/second² (m/s²), newton (N), second (s) and watt (W).

This module explores how energy is stored and transferred, the fundamental principle of energy conservation, the concept of efficiency, and the mechanisms of thermal energy transfer.

⚡ 1. Energy Stores and Transfers

🎯 Learning Outcomes (4.2, 4.5)

Describe energy transfers involving the 8 energy stores and 4 transfer pathways.
Describe everyday devices, explaining the transfer of input energy.

Energy is never created or destroyed, but it can be stored in different ways and transferred between stores.

Energy Stores

Chemical – bonds in food, fuels, batteries

Kinetic – moving objects

Gravitational PE – objects at height

Elastic PE – stretched/compressed objects

Thermal – particle energy due to temperature

Magnetic – interacting magnets

Electrostatic – separated charges

Nuclear – energy in atomic nuclei

Energy Transfers

Mechanically – a force does work (pushing, lifting)
Electrically – charges flow through a circuit
By Heating – temperature difference drives energy flow
By Radiation – energy as waves (light, sound)

💡 Example: A Bouncing Ball

Ball held high → Gravitational PE store
Falls: GPE decreases, KE increases (mechanical transfer); some to thermal (air resistance)
Hits ground: KE → Elastic PE + Thermal + Sound
Bounces up: Elastic PE → KE → GPE

💡 Example: Battery-Powered Torch

Battery: Chemical energy store
Switched on: Chemical energy transferred electrically to bulb
Bulb: Electrical → Light (useful, radiation) + Heat (wasted, heating)

🎾 Simulation: Bouncing Ball Energy Transfer

Watch how energy transfers between GPE, KE, and Thermal stores as a ball bounces.

Height: 5m

GPE0 J

KE0 J

Thermal0 J

Total0 J

🔄 2. Conservation of Energy

🎯 Learning Outcome (4.3)

Use the principle of conservation of energy.

Energy cannot be created or destroyed, only transferred from one store to another, or transformed from one form to another.

The total energy in a closed system remains constant. Energy can change forms, but the sum of all energy stays the same.

🕐 Simulation: Pendulum – GPE & KE Transfer

See how gravitational PE converts to kinetic energy and back. Toggle friction to observe energy dissipation.

Length: 1.5m Angle: 45° Friction

GPE0 J

KE0 J

Thermal0 J

Total0 J

📈 3. Efficiency & Sankey Diagrams

🎯 Learning Outcomes (4.4, 4.5)

Know and use: Efficiency = (Useful Energy Output / Total Energy Input) × 100%
Represent energy transfers using Sankey diagrams.

Efficiency = (Useful Energy Output ÷ Total Energy Input) × 100%

No device is 100% efficient; some energy is always dissipated, typically as heat.

🧮 Efficiency Calculator

Total Energy Input (J):

Useful Energy Output (J):

Sankey Diagram

The widths of the arrows are proportional to the energy amounts.

🌡 4. Thermal Energy Transfer

🎯 Learning Outcomes (4.6–4.8, 4.10)

Describe thermal energy transfer by conduction, convection and radiation.
Explain the role of convection in everyday phenomena.
Explain how emission/absorption relate to surface and temperature.
Explain ways of reducing unwanted energy transfer.

A. Conduction

Conduction transfers thermal energy through a substance without the substance moving. It mainly occurs in solids. Heated particles vibrate more vigorously, passing energy to neighbours. In metals, free electrons also carry energy rapidly.

💡 A metal spoon in hot tea – the handle becomes hot because energy is conducted along the metal.

Good conductors: metals. Poor conductors (insulators): wood, plastic, air.

🔥 Simulation: Conduction Race

Compare how fast heat travels through different materials. Watch the colour change from blue (cold) to red (hot).

0.0s

B. Convection

Convection transfers thermal energy in fluids (liquids and gases) by the movement of the fluid itself. Heated fluid expands, becomes less dense, and rises. Cooler fluid sinks, creating convection currents.

💡 Everyday examples:

Heating water in a kettle – element heats nearby water which rises
Room heaters – warm air rises, cool air replaces it
Sea & land breezes – differential heating of land and sea

C. Radiation

Radiation transfers thermal energy as infrared electromagnetic waves. It doesn’t require a medium and works through a vacuum (e.g., sunlight reaching Earth).

Dark, matt surfaces – good emitters & absorbers
Light, shiny surfaces – poor emitters & absorbers (good reflectors)
Hotter objects emit more radiation per second.

☀️ Simulation: Radiation Absorption Comparison

Compare how fast a dark matt surface and a shiny silver surface absorb infrared radiation.

0.0s

D. Reducing Unwanted Energy Transfer

Insulation reduces the rate of unwanted thermal energy transfer.

Method	How It Works	Example
Trapped Air	Air is a poor conductor; trapping it reduces conduction & convection	Loft insulation, cavity wall foam, double glazing
Reflective Surfaces	Shiny surfaces reflect infrared radiation back	Foil behind radiators, emergency blankets
Vacuum	No particles = no conduction or convection	Vacuum flask (Thermos)

🔬 5. Practical Investigations

🎯 Learning Outcome (4.9)

Investigate thermal energy transfer by conduction, convection and radiation.

Practical investigations are key to understanding thermal energy transfer. Below are typical setups with diagrams.

Investigating Conduction

Method: Attach pins with wax to rods of different materials. Heat one end equally. Record when each pin falls. Copper conducts fastest, glass slowest.

Investigating Convection in Liquids

Observation: Purple dye from potassium permanganate is carried upward by the warm rising water, showing the convection current path.

Investigating Convection in Gases

Observation: Smoke is drawn down the cold chimney, across the box, and up past the candle, making the convection current visible.

Energy Transfer