OCR (B) Physics GCSE Chapter 2: Sustainable Energy Flashcards

A set of vocabulary-style flashcards covering energy stores, power calculations, efficiency, electrical generation, and the National Grid based on OCR (B) Physics GCSE Chapter 2.

Energy Stores

The limited number of ways energy is considered as being stored: chemical, nuclear, kinetic, gravitational, elastic, thermal, electrostatic and electromagnetic.

Working and Heating

The processes by which energy is transferred from one store to another.

Power

Defined as the rate at which energy is transferred or the rate at which work is done, calculated using $P = \frac{E}{t}$ or $P = \frac{W}{t}$.

Watt ($W$)

The unit of power; an energy transfer of $1\,joule\,per\,second$ is equal to a power of $1\,watt$.

System

An object or group of objects; when it changes, the way energy is stored also changes.

Law of Conservation of Energy

The principle that energy can be transferred usefully, stored or dissipated but cannot be created or destroyed.

Dissipated Energy

Energy that is stored in less useful ways, often described as being 'wasted' during system changes.

Lubrication

The use of substances like oil to reduce friction between moving parts, thereby reducing energy lost as heat.

Thermal Insulation

Methods used to reduce the amount of useful thermal energy lost, such as using double glazing.

Thermal Conductivity

A property of a material where a higher value indicates heat travels through it more easily, increasing the rate of energy transfer by conduction.

Efficiency

The ratio of the useful work done by a machine to the energy supplied to it: $\text{efficiency} = \frac{\text{useful energy output}}{\text{total energy input}}$.

Sankey Diagrams

Diagrams used to show all energy transfers in a system, including dissipated energy, to help calculate efficiency.

Non-renewable Energy Resources

Sources including fossil fuels (coal, oil, gas) and nuclear fuel that cannot be replenished and are used for large-scale energy supplies.

Renewable Energy Resources

Energy sources that can be replenished as they are used, including biofuel, wind, hydro-electricity, geothermal, tidal, solar, and water waves.

Mains Electricity (UK)

An AC supply with a frequency of $50\,Hz$ and a potential difference of about $230\,V$.

Alternating Current (AC)

A type of current that continuously varies from positive to negative as the charge changes direction.

Direct Current (DC)

The movement of charge in one direction only, typically supplied by cells and batteries.

Live Wire

The brown wire in a plug that carries the alternating potential difference from the supply at $230\,V$.

Neutral Wire

The blue wire in a plug that completes the circuit, maintained at $0\,V$.

Earth Wire

The green and yellow striped safety wire at $0\,V$ that prevents an appliance from becoming live by carrying current to the ground if a fault occurs.

National Grid

A system of cables and transformers linking power stations to consumers across the UK.

Step-up Transformers

Transformers that increase the potential difference from the power station to the National Grid to decrease current and reduce energy loss.

Step-down Transformers

Transformers that decrease the potential difference from the National Grid to safer levels for consumers.