Energy Stores & Transfers Edexcel IGCSE Physics

Vocabulary flashcards covering energy stores, transfer pathways, principles of conservation, efficiency, and mechanisms of thermal energy transfer based on the lecture notes.

System

Defined in physics as an object or a group of objects.

Equilibrium

A state in a system where nothing changes, and so nothing happens.

Kinetic energy store

The energy store associated with moving objects.

Gravitational potential energy store

The store where objects gain energy when they are lifted through a gravitational field.

Elastic potential energy store

The energy store associated with objects that are stretched, squashed, or bent.

Magnetic energy store

The energy held by magnetic materials interacting with each other.

Electrostatic energy store

The energy held by objects with charge, such as electrons and protons, interacting with one another.

Chemical energy store

The energy store into or away from which energy is transferred during chemical reactions.

Nuclear energy store

The store from which atomic nuclei release energy during nuclear reactions.

Thermal energy store

The energy held by all objects; the hotter the object, the more energy it has in this store.

Mechanical working

An energy transfer pathway that occurs when a force acts on an object (e.g. pulling, pushing, stretching, squashing).

Electrical working

An energy transfer pathway involving a charge moving through a potential difference, such as a current.

Heating (by particles)

An energy transfer pathway from a hotter object to a colder one, such as through conduction.

Heating (by radiation)

An energy transfer pathway where energy is transferred by electromagnetic waves, such as visible light.

Principle of conservation of energy

States that energy cannot be created or destroyed, it can only be transferred from one store to another.

Dissipated energy

Energy that is spread out to the surroundings by heating and radiation; it is often not useful and described as wasted energy.

Efficiency

A measure of the amount of wasted energy in an energy transfer, defined by the formula: $\text{efficiency} = \frac{\text{useful energy output}}{\text{total energy output}} \times 100\%$

Sankey diagrams

Visual representations of energy transfers characterized by splitting arrows that show the proportions of the energy transfers taking place.

Conduction

The main method of energy transfer by heating in solids where atoms vibrate and bump into each other, transferring energy.

Convection

The main way that thermal energy is transferred through liquids and gases, which cannot occur in solids.

Thermal radiation

Infrared radiation emitted by all bodies; the hotter an object is, the more infrared radiation it radiates in a given time.

Conductors

Materials that transfer energy by heating effectively; metals are extremely good examples.

Insulators

Poor conductors used to prevent energy transfer by conduction; materials containing small pockets of trapped air are especially effective.

Delocalised electrons

Particles in metals that collide with atoms to help transfer vibrations through the material, speeding up thermal conduction.

Convection current

A motion resulting from a fluid being heated, causing it to expand, become less dense, rise, and eventually cool and sink.

Thermal equilibrium

The state where an object and its surroundings reach an equal temperature and heat loss ceases.

Fibreglass

A reinforced plastic material for loft insulation composed of woven material with glass fibres, utilizing trapped air as an insulator.

Cavity wall insulation

The process of filling gaps between external walls with a special foam made from blown mineral fibre filled with gas to lower conduction.