Generator:

In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. The source of mechanical energy may be a reciprocating or turbine steam engine, water falling through a turbine or waterwheel, an internal combustion engine, a wind turbine, a hand crank, compressed air or any other source of mechanical energy.

           

                                         

 Figure: Electric generator.

           

Working principle:

Electromagnetic induction is the production of voltage across a conductor moving through a magnetic field. So to get voltage, induction is very necessary. There are three conditions of proper induction.

1.      Conductor

2.      Magnetic fields and

3. Relative motion between them. 

 

 

3. Relative motion between them.    

Figure: Electromagnetic induction.

A metallic wire is warped around a metal bar called rotor. Rotor is connected with an external dc source for excitation. By the excitation, a magnetic field is produced where fluxes are flows from North Pole to South Pole.  When the rotor rotates the magnetic field also rotates. As a result the fluxes are cut by the conductors and voltage is induced from there. This is the Faraday’s law of electromagnetic induction.

Faraday's law of electromagnetic induction states that:

            “The electromotive force (EMF) produced around a closed path is proportional to the rate of change of the magnetic flux through any surface bounded by that path.”

Mathematically,

                       

Where, is the electromotive force (emf) in volts.

Φ_B is the magnetic flux in webers.

For the common but special case of a coil of wire, composed of N loops with the same area, Faraday's law of electromagnetic induction states that

Where,

 is the electromotive force (emf) in volts.

N is the number of turns of wire.

Φ_B is the magnetic flux in webers through a single loop.

Here, the negative sign indicates the direction which opposes the direction of motion according to Lenz’s law.

Applications of Faraday’s law:

Ø      Electrical generator

Ø      Moving coil microphone etc.

Power:

            Electric power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt. It is denoted by P.

Mathematically, P = VI = I²R

Where, V = voltage in volts (V)

             I = current in ampere (A)

             R = resistance in ohm (Ω)

In every power plant there are two types of power is generated.

1.      Megawatt (MW)

2.      MegaVARs (M-VAR)