What is the difference between AC and DC current?

Full Form of AC is Alternative current and of DC is Direct current. Direct current is flowing in one direction. Direct current example is battery which flows only in one direction. And Alternative current change it's direction in some microsecond time interval. Alternative current example is the current in your house.

How electric generator works?

In the previous article I had defined the mechanism of Electric motor. And in this article I am defining the mechanism of Electric Generator. Electric Generator works on same principal on which Electric motor works.
In Electric motor electric current is passing through wire in magnetic field which force the wire and rotates. And in Electric generator wires is rotated in Magnetic field which generates electric current.Below is the picture of electric generator.

You can see the Magnets and armature are in same ways as in motor. Here a handle is added with armature to rotate the armature.Armature ends are connected with conductor rings. Armature one end is connected to only one ring and another end is connected to only other ring. Both rings are touching brushes. When Armature rotates ring also rotates but brushes are stating just touching the ring. When Armature is rotated by handle then armature is entering and exiting in magnetic field. Principle is that, when you move a coil back and forth in magnetic field there is electricity generated in coil.So in this mechanism armature is entering and exiting in magnetic field so current is generated. And in the article of motor I have already described the Fleming's Left-Hand Rule. So in this architecture current direction is decided by direction of force and magnetic field. So current direction will change interchangeably.

You can see a bulb in picture. When armature rotates current will be generated and bulb will light.