We have seen how energy can be transferred and transformed by machines. When energy is transferred only part of it is transferred to where it is wanted and in the form it is wanted. The rest of the energy is wasted.
Many devices take in input energy in one form and (change) it to output energy in another form. They never transform all of the input energy to the output form we want or (move) it all to the place we want. We need to know how efficient devices are so that we can choose between them and to evaluate the effectiveness and cost effectiveness of methods used to reduce consumption. When buying a new kitchen appliance we often see efficiency ratings of A-E for different aspects of the appliance. In physics we use a percentage figure. We calculate this using the following equation:
When buying a new kitchen appliance we often see efficiency ratings of A-E for different aspects of the appliance. In physics we use a percentage figure. We calculate this using the following equation:
