explain construction,working and principal of ac and dc generator

We have a rectangular coil of area A placed in between magnetic poles. When the coil rotates there is a change in magnetic field lines passing through the area of the coil. We know a changing magnetic field produces an EMF. So, a current is induced within the rectangular coil. As the number of field lines through the coil is changing with the rotation of the coil, the induced EMF is also changing. The rotational motion of the coil is periodic. That is, the coil returns to its original position after every complete rotation. So, the EMF induced is also periodic. Hence, we have an alternating current within the coil. This is the working principle of an AC generator. For mathematical understanding, the relevant knowledge will be provided to you in higher standard.

hope this helps...thumbs up plz!!

Direct current (DC) motors are widely used to generate motion in a variety of products. Permanent magnet DC (direct current) motors are enjoying increasing popularity in applications requiring compact size, high torque, high efficiency, and low power consumption.

In a brushed DC motor, the brushes make mechanical contact with a set of electrical contacts provided on a commutator secured to an armature, forming an electrical circuit between the DC electrical source and coil windings on the armature. As the armature rotates on an axis, the stationary brushes come into contact with different sections of the rotating commutator.

Permanent magnet DC motors utilize two or more brushes contacting a commutator which provides the direct current flow to the windings of the rotor, which in turn provide the desired magnetic repulsion/attraction with the permanent magnets located around the periphery of the motor.

The brushes are conventionally located in brush boxes and utilize a U-shaped spring which biases the brush into contact with the commutator. Permanent magnet brushless dc motors are widely used in a variety of applications due to their simplicity of design, high efficiency, and low noise. These motors operate by electronic commutation of stator windings rather than the conventional mechanical commutation accomplished by the pressing engagement of brushes against a rotating commutator.

A brushless DC motor basically consists of a shaft, a rotor assembly equipped with one or more permanent magnets arranged on the shaft, and a stator assembly which incorporates a stator component and phase windings. Rotating magnetic fields are formed by the currents applied to the coils.

The rotator is formed of at least one permanent magnet surrounded by the stator, wherein the rotator rotates within the stator. Two bearings are mounted at an axial distance to each other on the shaft to support the rotor assembly and stator assembly relative to each other. To achieve electronic commutation, brushless dc motor designs usually include an electronic controller for controlling the excitation of the stator windings.

i want in limited and simple,easy ans not such a big but thanks ayushi and if u know then give the ans how i want