GCSE PHYSICS - MAGNETISM AND ELECTROMAG - LESSON 18 - electromag induction ac generator

Understanding Simple AC Generators

Overview of Electromagnetic Induction

• The previous lessons covered electromagnetic induction, focusing on generating electrical potential differences in conducting cables and loops.

• Introduction to a simple AC generator design featuring two permanent magnets and a single conducting loop representing a coil.

Components of the Generator

• Description of the coil as a tightly wound structure with multiple loops; represented here by a single loop for simplicity.

• Explanation of slip rings and graphite brushes that collect current generated by the rotating coil mounted on an axis called the rotor.

Mechanism of Current Generation

• The coil rotates through the magnetic field between two permanent magnets, generating alternating current (AC).

• Brushes rub against slip rings to collect the generated current from the rotating coil.

Current Behavior During Rotation

• When the coil is horizontal, it cuts through magnetic field lines, resulting in maximum current generation.

• In vertical position, sections of the coil move parallel to magnetic field lines, leading to zero current generation at this moment.

Alternating Current Characteristics

• As rotation continues past vertical, direction of current changes due to movement; after half-turn, maximum current flows in opposite direction.

• Continuous rotation results in an alternating current waveform; joining points reveals sinusoidal variation typical for AC.

Effects of Increasing Coil Rotation Speed

• Doubling rotation frequency leads to increased frequency and larger output current generated by the generator.