Induced Potential, Transformers and the National Grid

• When an electrical conductor moves relative to a magnetic field, a potential difference is induced across the ends of the conductor.
• When an electrical conductor is placed in a changing magnetic field, a potential difference is induced across the ends of the conductor.
• For an induced potential difference to cause a current flow, the conductor must form a closed loop or be part of a complete circuit.
• For current to be induced in the secondary coil, the magnetic field in the core must be continuously changing.
• An alternating current flows through the primary coil of a transformer, inducing a changing magnetic field in the core.
• For the magnetic field to be changing, the current in the primary coil must be alternating.
• The changing magnetic field in the core induces a current to flow in the secondary coil.
• The electrical power input of a 100% efficient transformer is equal to the electrical power output.
• A transformer works by transferring energy between two circuits through the magnetic field of the transformer's coils.
• The generator effect is used in alternators to produce alternating-current and in dynamos to produce direct-current.
• The direction of the magnetic field produced by an induced current is such that it opposes the change that induced the current.
• The makeup of a basic transformer consists of a primary coil and a secondary coil of wire wrapped around an iron core.
• Iron is used as the core for a transformer because it is easily magnetised.
• A microphone takes advantage of the generator effect, converting the pressure variations in sound waves into alternating current in a circuit.