Science 10 with CSS teacher

Efficiency = the measure of how well a device transfers energy into the form we want.

Even though energy is always conserved, it's not always in the form we want.

When we convert energy, some energy always ends up in a form that we consider wasted energy. The question of how much of the energy is useful is of interest to us, especially as we look to become less wasteful.

As a rule, every energy conversion is less than 100% efficient. The energy is not destroyed, it is just transformed into something that is not that useful such as heat or sound.   Feel the back of your computer - can you feel energy being released that is not very useful to the computer.

If you switch the ratio of Useful Output and Total Input in the formula, you may get an efficiency that is greater than 100%. This would indicate that your machine has created energy, which is a violation of the Law of Conservation of Energy. If this happens, revisit your technique.