+

Energy Transfer

Noadswood Science, 2011

+Energy Transfer

To understand energy transfers, and to be able to draw sankey diagrams

Wednesday, April 19, 2023

+Energy

What is energy?

What types of energy are there?

+Energy

Energy is the ability to ‘do some work’ - everything that happens needs energy (e.g. heating; cooking; lighting; movement of vehicles; and keeping us alive)!

Energy cannot be created or destroyed, only transferred from place to place in a variety of ways

+Types Of Energy

Electrical energy - a current in a circuit etc… Light energy - from the sun; a light bulb etc… Sound energy - from a loudspeaker; a drum etc… Kinetic (movement) energy - anything which moves! Nuclear energy - transferred during a nuclear reaction Thermal (heat) energy - transferred from hot objects to

colder ones Radiant heat (infra red) energy - transferred as

electromagnetic radiation by hot objects Gravitational potential energy - possessed by anything

with the ability to fall Elastic potential energy - stretched springs; elastic and

rubber bands etc… Chemical energy - possessed by food; fuels; batteries

etc…

+Energy

Newton’s Cradle – example of energy being transferred…

+Experiment

Your task is to move around each of the stations, answering the questions at each point (you have 3 minutes per station)…

Stations: - Signal generator Microphone Kettle with windmill Air bazooka Fire Slinky Cordless screwdriver Hair straighteners

+Signal Generator

What are the energy transfers for the signal generator? Electrical Light / Sound

Which forms of energy are wasted? Heat through circuits

How could you make it more efficient? Better insulated wires etc…

Are there still energy transfers taking place, even when you cannot hear the sound? Yes – visual as well as heat transfer through circuitry +

sounds which our ears are unable to detect

+Microphone

What are the energy transfers for the microphone? Sound Electrical

Which forms of energy are wasted – where do these go? Heat through circuitry to surroundings

How could you make it more efficient? Better insulated; more sensitive cone which will not waste

as much energy

Can you think of any other devices which use these energy transfers? Opposite found in loudspeakers; our own ears transfer

sound energy into electrical impulses

+Kettle & Windmill

What are the energy transfers for the kettle and windmill? Chemical Electrical Heat Kinetic Electrical

Which forms of energy are wasted – where do these go? Heat to surroundings; sound to surroundings through windmill

movement

How could you make it more efficient? More aerodynamic windmill; insulated kettle to stop heat loss

This is very similar to how electricity is generated – can you think how you could use this method to make electricity? Generator connected to windmill transferring kinetic to electrical

+Air Bazooka

What are the energy transfers for the air bazooka? Potential Kinetic

Which forms of energy are wasted – where do these go? Heat and sound to surroundings

How could you make it more efficient? Energy store could be more efficient; delivery system

pushing missle out

Can you think of any other devices which use these energy transfers? Steam catapults on aircraft carriers; bullets (chemical

stores)

+Fire

What are the energy transfers for using sticks to make fire? Chemical Heat

Which forms of energy are wasted – where do these go? Light and sound to surroundings

How could you make it more efficient? Different fuel to burn more efficiently (i.e. petrol over wood)

Why is it important to make things more energy efficient? Ensures we get best value for money from fuel – most fuels

are non-renewable so we need to get the most from them that we can / less fuel = more environmentally beneficial

+Slinkey

What are the energy transfers for a slinky falling down some stairs? Gravitational potential (elastic potential) Kinetic

Which forms of energy are wasted – where do these go? Sound to surroundings and some heat through movement /

friction

How could you make it more efficient? Stop springs colliding causing sound

Can you think of another device which uses these energy transfers? Hydroelectric power relies on gravitational potential to kinetic

+Cordless Screwdriver

What are the energy transfers for the cordless screwdriver? Electrical Kinetic

Which forms of energy are wasted – where do these go? Sound and heat to surroundings

How could you make it more efficient? Improved motor with less frictional loss (heat loss)

Can you think of any other devices which use these energy transfers? Remote control cars; watches etc…

+Hair straighteners

What are the energy transfers for the hair straighteners Electrical Heat

Which forms of energy are wasted – where do these go? Sound; heat loss through the non-contact points

How could you make it more efficient? Better conductivity of materials

Why do you think some straighteners are better than others? Dependent upon conductivity of material at point of contact

with hair – better conductors heat up quicker and transfer their energy to the hair quicker and more effectively

+Energy Transfer

Different types of energy can be transferred from one type to another

Energy transfer diagrams show each type of energy, whether it is stored or not, and the processes taking place as it is transferred

+Energy Transfer

Different types of energy can be transferred from one type to another

Energy transfer diagrams show each type of energy, whether it is stored or not, and the processes taking place as it is transferred

+Sankey Diagrams

Sankey diagrams show the relative amounts of each type of energy

They summarise all the energy transfers taking place in a process – the thicker the line or arrow, the greater the amount of energy involved

Sankey diagram of a light bulb

+Wasted

Energy can be 'wasted' during energy transfers

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

Energy that is ‘wasted’ (e.g. heat energy from an electrical lamp) does not disappear – instead it is transferred to the surroundings, spreading out so much that it becomes difficult to do anything useful with

+Lamps - Ordinary

Ordinary electric lamps contain a thin metal filament that glows when electricity passes through it – however, most of the electrical energy is transferred as heat energy instead of light energy: -

+Lamps – Energy Saving

Modern energy-saving lamps work in a different way – they transfer a greater proportion of electrical energy as light energy: -