Descibe[/B] in detail the contruction of a piezoelectric device (ultrasound machiene) and how it works. And explain why the singal from that device need amplification
The Attempt at a Solution
Electrical current passes to the piezoelectric crystal (non-conductive material, no charge in any arrangement) and electrical pressure is experienced. The pressure causes the crystals to contarct/expand and virbate which causes the molecules to move causing an imbalance of charge making one electrode more positive then the other producing soundwaves. These soundwaves reflex from organs etc and are recieved by the transducer probe. The pressure from the waves casue the molecules in the crystals to move causing an imbalance in charge making one metal plate positively charged and the other negitively charged creating a potential difference producing a current which flows down the cable.
Amplification is used to increase the size of the electrical pulses coming from the transducer after an echo is received. This is becasue the electrical signal is too small to produce a detailed image
(I am really struglying with why the signal needs amplifying as I can't find an explanation)