Energy and Energy Efficiency Flashcards
(12 cards)
State the law of conservation of energy
The law of conservation of energy states that energy cannot be created or destroyed, only transferred and transformed.
Describe energy efficiency in terms of input and output of energy
Energy efficiency is the measure of how much input energy is converted into useful output energy.
Energy efficiency is based on how much useful energy is produced from the amount of input energy, and how much energy is wasted.
What is input and output energy?
Input energy = The energy that is put into a device/system for it to operate.
Output: The energy that a device/system produces. There is useful output energy and wasted output energy.
What is the formula to calculate energy efficiency? (%)
Energy efficiency =
useful energy output/total energy input x 100 %
List the practical methods that improve energy efficiency
Insulation, reducing friction, and switching to LED lighting.
How does insulation improve energy efficiency?
Insulation improves energy efficiency by reducing heat transfer.
It acts as a barrier, preventing heat from escaping in winter and entering in summer.
This means less energy is needed to heat or cool a home.
Provides substantial resistance to heat flow either in to or out of a building. This means that the need for heating and cooling is minimised.
How does reducing friction improve energy efficiency?
Friction in engines and machines contributes to energy loss. Friction is a source of energy waste When two surfaces rub against each other, some of the energy of motion is converted into heat due to friction. Reducing friction (e.g using lubricant) stops the energy being lost, improving energy efficiency.
How do LED lights improve energy efficiency?
They improve energy efficiency by converting most of their energy into light rather than heat compared to traditional bulbs. LED lightbulbs use around 85% less energy and last longer than traditional incandescent bulbs.
What is energy measured in?
Joules (J)
What are the 2 main types of energy?
Potential energy (stored energy) & Kinetic energy (energy of motion)
Give examples of potential and kinetic energy
Potential:
- Gravitational potential energy
- Chemical energy
- Elastic potential energy
- Nuclear energy
Kinetic:
- Electrical energy
- Light energy
- Heat energy
- Sound energy
What is potential energy?
Energy stored in an object.
