| We supply electrical energy to an electric motor. An efficient motor transfers most of this energy as kinetic energy (useful work). Only a small fraction is wasted as it heats up the surroundings. We can show this in a Sankey diagram (picture 6). The size of the arrows represents the amount of each type of energy. Energy is lost as the electric current flows through the motor’s coils. The wire coils have electrical resistance; the greater the resistance, the harder it is for the current to flow and the more energy is wasted. Copper is a good metal to use for a motor’s coils because: - it has less resistance than almost any other metal (see conducting properties)
- it is easily made into wires
- it is not too expensive
- it can survive to a high temperature
- it can be easily recycled when the motor is replaced.
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