The impedance (Z) is a measure of opposition that a circuit to a current when a voltage is applied. The impedance extends the concept of resistance circuits alternating current (AC), and has both magnitude and phase, unlike resistance, which has only magnitude. When a circuit is powered with direct current (DC), there is no distinction between the impedance and resistance; the latter can be thought csa impedance with zero phase angle.

One hertz is one cycle per second, meaning repeating cycle as an event. For example, hertz is applied physics measuring the number of times for a second wave (either acoustic or electromagnetic) is repeated or can be applied, among other uses, to ocean waves that reach the Beach vibrations per second or a solid. The quantity that measures the frequency hertz is called,in this regard, the inverse of the period. One hertz is an oscillation frequency of suffering a particle over a period of one second.

ng-Lee used in Europe for terrestrial receivers. It requires a little more attention to the correct installation of the cable male with Belling-Lee type and should be attentive to the quality of the connector and match the size of connector cable.

Although there are infinity tips as manufacturers or type of use, these are the most commonly tips used in the electronics industry, hardware or electricity.

1. Slot: Characterized by its flat and elongated tip.

2. Phillips: It may be the most used, its tip is shaped like a four-pointed star. Also called commonly screwdriver

3. Pozidriv: Like the previous model, but with a twist. Inside it has 4 slots in a star more.

4. Torx: Widely used in vehicles, its shape is a star with 6 points.

5. Security Torx: Same as above, but inside has a pin.

6. Hex: Point-shaped or hexagon Allen calls. Such tips are distinguished from the rest because they are able to withstand higher torque strength.