antonio franco

Electromagnetic generators transform mechanical energy into electricity. There are two types of generators dynamos and alternators. Dynamos A dynamo consist of a magnet and a rotary coil, The coil is located between the two poles of the magnet.  The ends of the coil have two semi-circular conductors, with form the conmutator. These conductors are attached to carbon brushes, wich in turn are connected to electrical wires. When electricity is applied to the coil, it rotates and begins to generate direct current in the coil. Alternator A simple alternator is almost identical to a dynamo, except for the comnutator, wich consist of two metallic rings conected to carbon brushes. instead of direct current this produces alternating current.

Inside a fluorescent tube, there is a metalic filament, normally made of tungsten. There is also an inert gas, such as argon, and a small amount of mercury. When an electric current passes through the filament, electrons are emited  into the inert gas.

 When an electric current passes through the metalic filament of a light bulb, it produces light: It is callled incandescense

The energy that an electric current produce as heat is called the joule effect. It is expressed by the following formula: E=(IxI)xRxT

 There is an important diference between alternating and direct current. Alternating current can be modified by a transformer. This allows us to transfer electrical energy at very high voltage  and over hundred of km, without losing any energy as heat. Transformer consist of two winding made of copper wire. If we apply an alternating current to one of them, it will produce a certain voltage in the other.  V1/V2=N1/N2

 when we connect  a lamp to a socket, the result is the same as with a battery: The bulb ligths up. However, the electrons behave in very different way in this case. The flow of electrons  changes directions 50 times every second, as if the positive  and negative poles of the socket were constantly changin places.