- Generator Working Principle: An electric generator works by moving a conductor through a magnetic field, inducing an electromotive force (EMF) based on Faraday’s law of electromagnetic induction.
- Fleming’s Right Hand Rule: This rule determines the direction of EMF, using thumb for motion, first finger for magnetic field, and second finger for EMF direction.
- AC vs. DC Generators: AC generators use slip rings to maintain the alternating nature of the generated current, whereas DC generators use a commutator to rectify the current.
- Single Loop Generator Model: The simplest form of an electric generator, where rotating a conductor loop between magnetic poles alters the direction of induced EMF.
- Energy Conversion: Electric generators convert mechanical energy into electrical energy, crucial for various applications from household to industrial uses.
When a conductor moves in a magnetic field, an emf appears across the conductor. A rotating electric generator converts mechanical energy to electrical energy by that Faraday induction, including machines such as portable generators.
According to Faraday’s law of electromagnetic induction, when a conductor links with a changing flux, an emf is induced across it. The size of that emf depends on the rate of change of flux linkage. The direction of the induced emf in the conductor follows Fleming’s Right Hand Rule. Stretch the thumb, first finger and second finger of the right hand at right angles. Align the thumb with the motion of the conductor in the magnetic field and the first finger with the field. The second finger then points in the direction of the emf.
The same rule shows how electricity appears when a single conductor loop rotates in a magnetic field.
When one side of the loop faces the north pole, its instantaneous motion is upward, so Fleming’s Right Hand Rule gives an inward emf.
At the same time the other side faces the south pole. The conductor moves downward, so Fleming’s Right Hand Rule gives an outward emf.
Each side of the loop therefore passes the north pole and the south pole in turn. Under the north pole motion is upward. Under the south pole the conductor moves downward. The loop emf therefore reverses twice per revolution. That single-loop machine is the basic conceptual model of an electric generator. The induced emf can be taken off in two ways.
Connect a slip ring to each end of the loop. A load then connects through brushes that rest on those rings. The alternating electricity in the loop reaches the load. That machine is an AC electric generator.
The same rotating loop can feed a load through a commutator and brushes, as in the animation below. The electricity in the loop (the armature of this single-loop model) is then rectified by the commutator, so the load sees DC. That arrangement is the basic model of a DC generator.
