P1.2 - Energy and efficiency

• Energy can be transferred usefully, stored, or dissipated, but cannot be created or destroyed

• When energy is transferred only part of it may be usefully transferred, the rest is 'wasted'
• Useful energy is energy in the place we want it and in the form we need it
• Wasted energy is energy that is not useful energy
• Wasted energy is eventually transferred to the surroundings, which become warmer. The wasted energy becomes increasingly spread out and so less useful

Efficiency = useful energy out        (x100)

                         total energy in

Efficiency = total power out           (x100)

                          total power in