Energy and Efficiency Flashcards
What is the difference between a Sankey diagram and an Energy Transfer diagram?
Energy Transfer diagrams only show the useful energy transfers. A Sankey diagram shows the total energy input, the useful energy and wasted energy.
How do you calculate the amount of electrical energy transferred to an appliance?
E= Pxt
Energy transferred (E) measured in kilowatt-hours, kWh
Power (P) measured in kilowatts, kW
Time (t) measured in hours (h).
State two facts about energy.
Energy can be transferred usefully, stored or dissipated. It cannot be created or destroyed.
What is magnetic energy?
Magnetic energy us energy in magnets and electromagnetics.
What is kinetic (movement) energy?
Kinetic (movement) energy is energy in moving objects.
What is heat (thermal) energy?
Heat (thermal) energy is energy used in hot objects.
What other name is ‘light’ also known by?
Light is also called radiant energy.
What is gravitational potential energy (GPE)?
GPE is stored energy in raised objects.
What is chemical energy?
Chemical energy is stored energy in fuels, food and batteries.
What is sound energy?
Sound energy is energy released in vibrating objects.
What is electrical energy?
Electrical energy is energy in moving charges or static electric charges.
What is electrical potential energy?
Elastic potential energy is stored energy in stretched or squashed objects.
What is nuclear energy?
Nuclear energy is energy stored in nuclei of atoms.
What is the efficiency of a device?
The efficiency of a device is the proportion of the energy supplied that is transferred in useful ways.
How do you calculate efficiency?
Efficiency = useful energy out ÷ total energy in (for a decimal efficiency). Note that the efficiency of a device will always be less than 100%.
