Investigating the effectiveness of insulating materials
Dr Maggie Aderin-Pocock and Dr Alex Lathbridge investigate the effectiveness of insulating materials
Energy conservation and dissipation
The capacity for doing work. can be transferred usefully, stored or The spreading out and transfer of energy stores into less useful forms, such as thermal energy causing the surroundings to heat up. Dissipated energy is often referred to as 'wasted' energy, since it is not transferred to a useful output. , but it cannot be created or destroyed.
Learn more on conservation and dissipation of energy in this podcast
Listen to the full series on BBC Sounds.
Conservation
In all cases, energy comes from one store and is transferred to another store. This means that all the energy in the Universe was present at the The scientific theory that describes the early development of the Universe. and will still be around at the very end of time.
Dissipation
When a child comes down a slide, she begins to pick up speed. Energy is shifting from a gravitational store into a kinetic store.
However, not all of the energy is transferred into the kinetic store. As some work is done pushing against the rough surface of the slide, some of the energy is transferred to the slide and raises the temperature of the slide.
No An object or group of objects. is perfect. Whenever there is a change in a system, energy is When something is moved from one place to another. This may be people, objects or energy. and some of that energy is dissipated.
The process of energy being transferred, or lost, to the surroundings. is a term that is often used to describe ways in which energy is wasted. Any energy that is not transferred to useful energy stores is said to be wasted because it is lost to the surroundings.
Electrical cables warming up are a good example of this. It is not useful to have hot wires behind a television as energy is dissipated to the surrounding air.
In a mechanical system, energy is dissipated when two surfaces rub together. Work is done against A force that opposes or prevents movement and converts kinetic energy into heat. which causes heating of the two surfaces - so the internal (thermal) energy of the surfaces increases. Adding A lubricant is anything which reduces the friction between two surfaces. between the surfaces reduces this friction and so less heat is wasted, like on a conveyor belt for example.
In an electrical context new types of component can be more energy-efficient such as LED light bulbs as opposed to filament lamps, and using these cause less energy to be wasted.
Examples of dissipation
Energy is usually lost by heating up the surroundings though sometimes energy is dissipated as sound waves.
The ways in which energy is dissipated depends on the system:
- for a radio or set of speakers the Energy transferred by an electric current. is transferred into useful sound waves and infrared radiation is dissipated - ie wasted as heat energy
- for a tumble dryer, the electrical work is transferred into useful internal (thermal) energy which helps to dry clothes - energy is dissipated by sound waves and by thermal energy of the surroundings which is not usefully used to dry the clothes
