Most AC electric motors function by inducing electricity into the rotating part of the motor (contrasting with DC motors which have commutators and brushes). These slides provide a brief overview of the structure and function of AC induction motors.

# Category Archives: motors & generators

# Transformers

It is far more efficient to transmit electricity at high voltages (and low currents), but we often require quite small voltages within electronic devices. We achieve these numerous and necessary changes in voltage using transformers.

These slides introduce and explain the function of transformers, with some comment on sources of energy loss and associated design strategies.

# Generators

These slides briefly outline the structure and function of AC and DC generators.

# Applications of Lenz’s Law

These slides outline a number of real world applications of Lenz’s law, including electromagnetic braking, induction cooktops and back emf in electric motors.

# Lenz’s Law and Eddy Currents

According to Faradays law, a changing magnetic field will induce an emf. If the emf flows in a current, another magnetic field will be created (similar to how an electromagnet works). The new field and original field oppose each other – and this is known as Lenz’s law. It is required by the conservation of energy.

The slides explain Lenz’s law, and also discuss the related concept of eddy currents.

# Faraday’s Law and Magnetic Flux

During the 1830’s Michael Faraday was trying to create electricity using magnets (because a connection between electricity and magnetism had been recently discovered). He discovered that a changing magnetic field will induce an EMF into a conductor. This became known as Faraday’s law, and underpins all electrical generators.

These slides discuss Faraday’s law, and also provide an overview of magnetic flux (measured in Webers) and magnetic flux density.

# Parallel conductors

When current flows through parallel conductors, a force exists between them, since each current produces a magnetic field around its conductor. These slides provide an overview for determining the magnitude and direction of such forces.