Electronics, motors and generators

• AC current: Electrons alternate in direction, and the poles (positive and negative) of a conductor also alters. This is generated using a rotating coil.

  Pros: Can be transferred from high to low voltage. It can travel long distances

  Cons: Cannot be stored in battery, must always be generated
• AC current is perfect for households since it can travel long distances, and is able to change voltage which is suitable for geographical locations and for the different devices and their required currents in an outlet.
• DC current: provides a constant voltage, flows from negative to positive, can be stored in batteries. However, it cannot be used across long distances since due to transmission losses.
• Magnetic induction is a phenomenon where an electric current travelling through a conductor creates a magnetic field.
• Induction motors include stators and rotors, and sometimes brushes
• The stator in an induction motor provides an electromagnetic field that is constantly changing due to the nature of AC currents. The stator in an electric motor simply consists of a magnet that is induced by the rotor (the rotor provides the moving electromagnetic force)
• The rotor in the induction motor is simply a magnet that moves after being induced by the electromagnetic stator.
• The rotor in an electric motor is a coil that induces the magnet. The coil provides an electromagnetic (changing) field, meanwhile the stator is simply a magnet.
• The DC motor needs a commutator to function, as it provides an artificial change that ensures the rotor continues to move. The AC motor provides synchronisation due to phase shifts.
• Brushes ensure that the rotor is always in contact with the stator to ensure it stays in place. However, they can reduce efficiency, since it slows down the motor.
• Back EMF (electromotive force) is a phenomenon which is directly related to the speed of the motor and is the leading reason as to why the motor cannot spin indefinetly/exponentially fast. The higher the speed, the more the back EMF, the more resistance to increase speed.