P1.2 Energy and Efficiency NOT FINISHED Flashcards
Where is electrical energy found?
Whenever a current flows
Where does light energy come from?
From the Sun, light bulbs, etc
Where does sound energy come from?
From loudspeakers, or anything noisy
Where is kinetic energy found?
Anything that is moving, has it
Where does nuclear energy come from?
It is released from nuclear reactions
Where is thermal (heat) energy found?
It flows from hot objects to colder ones
Where is gravitational potential energy found?
In anything which can fall
Where is elastic potential energy found?
Stretched springs, elastic, rubber bands, etc
Where is chemical energy found?
Food, fuels, batteries, etc
What are gravitational P’, elastic P’ and chemical energy all forms of?
Stored energy, the energy is not doing anything but it is waited to be turned into other forms
What is the conservation of energy principle?
Energy can be transferred usefully from one form to another, sored or dissipated - but it can never be created or destroyed
What is the energy supplied to a device called?
The energy input
What is the useful energy transferred by a device called?
The energy output
What determines the efficiency of a device?
The less energy that is wasted, the more efficient that device is
What is the formula for finding efficiency in terms of energy?
Efficiency = useful energy out / total energy in
What is power?
The amount of energy transferred per second
What is the formula for finding efficiency in terms of power?
Efficiency = useful power out / total power in
What is efficiency measured in?
It can be a decimal or percentage
What do you need to remember about wasted energy?
Most devices aren’t 100% efficient and the wasted energy is usually spread out as heat
What is an example of a 100% efficient device?
An electric heater, as it uses the ‘wasted’ heat energy as its useful energy
What is useful energy?
Concentrated energy
What eventually happens to the useful and wasted energy output of a device?
It ends up as heat which is then transferred to cooler surroundings and becomes less concentrated - here it dissipates
What is meant by ‘energy dissipates’?
It doesn’t lose its original energy value, it just becomes more spread out and harder to collect
How can the wasted energy of an appliance be reused?
The wasted energy of a device can be used to heat a liquid which can then be used elsewhere
