The film speed sensitivity physically defined as the inverse of that required to attain a predetermined response input system. The scale was created for photographic emulsions but has also been adapted for electronic digital photography. In the one case as the other high sensitivity is the counterpart of loss of picture quality. The exposure index or senbility of a film is indicated by the scales ASA, DIN, ISO or GOST (Soviet scale currently unused). The ISO system is actually merging the ASA and DIN systems, because it indicates both values ??(so, for example, a film will have a sensitivity ISO 100/21).

We can find 3 types of jack connector, monaural TS connector (tip-sleeve), TRS (tip-ring-sleeve) and TRRS stereo plug (tip-ring-ring-sleeve) which is used in most mobile devices, tablets, MP3 etc ...
We can difference these 3 types of connectors according to their diameter:

1. 6.35 mm jack connector or TS.
2. 3.5mm minijack connector or TRS, is the most common, usually used in headphone's output of portable devices.
3. 2.5mm jack connector or TRRS.

It consists of a maximum of three connecting parts being called the largest mass or negative polarity and two smaller size located more towards the end of the connector,
The called positive that correspond to each channel, such three-part plug can transmit signals in two separate channels, also known as stereo signals. There's a mono version, consisting of only two parts, a negative and a positive.

A. Protector
B. Stem
C. Ring
D. Tip
E. Kindred
F. Ring (Signal Right)
G. Tip (Signal Left)