Energy stores & Transfers (Edexcel GCSE Physics): Revision Notes

Energy Stores & Transfers

Energy Stores

Energy is stored in different types of energy stores. The main types include:

• Nuclear Energy: Stored inside the nuclei of atoms. This energy is released during nuclear reactions, like in the sun or in nuclear power plants.
• Thermal Energy: Stored in an object due to its heat. The hotter the object, the more thermal energy it has.
• Electrostatic Energy: Stored by two charges that are attracting or repelling each other. Similar to magnetic energy but involves charged particles instead of magnets.
• Chemical Energy: Energy stored in the chemical bonds between atoms and molecules. Found in food, fuels, and batteries.
• Magnetic Energy: Stored by two magnets that are either attracting or repelling each other. If the magnets are closer together, the energy in the store is higher.
• Elastic Potential Energy: Stored in an object that has been stretched or compressed. For example, a stretched spring or a compressed rubber band has stored elastic potential energy.
• Kinetic Energy: Stored by an object that is moving. The faster an object moves, the more kinetic energy it has.
• Gravitational Potential Energy: Energy stored in an object when it is raised above the ground.

Energy Transfer Between Stores

Energy can be transferred between these stores when a system changes.

Energy Transfers

Reducing Energy Waste

• Lubrication:
  • Example: Oil in a motor reduces friction, meaning less energy is lost as heat.
• Thermal Insulation:
  • Example: Double glazing reduces the amount of thermal energy lost from a building.

Thermal Conductivity

• Higher thermal conductivity in a material allows heat to travel through it more easily, increasing the rate of energy transfer by conduction.
• Thermal Conductivity in Buildings:
  • The rate of cooling is slower if the walls are thick and have low thermal conductivity.
  • If walls are made of thin metal sheets, heat would be lost very quickly.

Efficiency

Efficiency=Total energy inputUseful energy output=Total power inputUseful power output

• Increasing Efficiency:
  • Reduce waste output: Methods like lubrication and thermal insulation help.
  • Recycle waste output: For example, thermal waste can be captured and reused as input energy.

Increasing Efficiency of Energy Transfer

• The lower the thermal conductivity of a material, the less energy is lost as heat.
• Walls: Insulating material in the wall cavity helps reduce thermal energy loss.
• Windows: Double-glazed windows minimise heat loss.
• Roof: Loft insulation helps retain heat inside the house.

Diagram