lesson 7; calculating energy efficiency

Question 1

Most energy transformations convert energy

Answer 1

from one form into multiple other forms. Some of the forms that it is converted into are not very ‘useful’ and are sometimes classified as wasted energy.

Question 2

The efficiency of an energy transformation is

Answer 2

the percentage of the initial energy that is converted into the desired form.

Question 3

Energy efficiency =

Answer 3

Energy efficiency = useful energy output/energy input X 100%

Question 4

output energy

Answer 4

• Laptops require an input of electrical energy to do useful work. They transform electrical energy into light, sound and heat. The energy supplied to the device is called the INPUT energy and the energy that comes out of the device is called the OUTPUT ENERGY.

Question 5

laptop example

Answer 5

• The production of sound and light is part of the purpose of a laptop BUT the production of heat is not. The output energy that is not put to its intended use is called WASTE ENERGY. Output energy that is put to its intended use if called USEFUL energy. All energy transfers and transformations involve some waste energy and it is in the form of heat and sometimes sound.

Question 6

why is energy efficiency important

Answer 6

• The more energy wasted by a device, the more energy we need to supply. This is an issue because it could mean a larger contribution to climate change.
• We are able to calculate how much input energy is transformed into useful energy and this is called the Energy Efficiency of the device.
• The higher the percentage, the better the energy efficiency is
• Energy efficiency is calculated by dividing the useful output energy by the total unput energy and expressing the result as a percentage