Energy Matters: Source to Consumer

A voltage is induced in a conductor whenever the conductor moves in a magnetic field, or, if the conductor remains stationary, the magnetic field changes.

dynamos

to change the magnitude of an a.c. voltage

two coils of wire wrapped around a soft iron core

• rotor
• iron core
• stator coil

• a permanent magnet.
• when this rotates there is a voltage induced in the stator coil

• strength of the magnetic field
• number of turns on the coil
• relative speed of motion

• the rotor uses an electromagnet instead of a permanent magnet to produce a stronger magnetic field.
• the stator also consists of several coils in order to generate large currents

• transformers are used to reduce power losses in electrical transmission.
• this is done by operating the transmission lines at a high voltage.

• to increase the voltage from the power station.
• overhead lines then carry electricity round the country
• step-down transformers are then used to reduce the voltage to suitable levels for industries and homes

• energy can be lost
• heat losses in coils
• magnetising/ demagnetising losses
• eddy currents in the core
• sound losses

• due to the resistance of the line
• to reduce the current and therefore the power losses, the voltage is stepped-up