Efficiency

The video tutorial explains the concept of energy efficiency, which is calculated by dividing the useful energy output by the total energy input and converting it into a percentage. It highlights that loudspeakers have a low efficiency of around 3%, with most energy lost as heat. In contrast, the human body is highly efficient at converting food into energy, with a sprinter being four times more efficient than a motorbike.

How is energy efficiency calculated?

• By adding the useful energy output to the total energy input

• By subtracting the total energy input from the useful energy output

• By dividing the useful energy output by the total energy input

• By multiplying the total energy input by the useful energy output

What percentage of electrical energy is typically converted into sound by loudspeakers?

• 10%

• 50%

• 97%

• 3%

What happens to the majority of electrical energy supplied to loudspeakers?

• It is converted into light

• It is stored for later use

• It is converted into sound

• It is lost as heat

In terms of energy conversion, how does a sprinter compare to a motorbike?

• A sprinter is four times more efficient

• A sprinter is less efficient

• A sprinter is equally efficient

• A sprinter is twice as efficient

What is the primary source of fuel for the human body to convert into energy?

• Food

• Solar power

• Wind energy

• Electricity