Question on Piezoelectric effect

[Ukitake Jyuushirou]

I was reading about the piezoelectric effect in ultrasound and I am not sure how it works. Do you apply a voltage to the quartz crystal to achieve an alternating electric field or mechanical stress to the crystal? How does applying stress to the crystal create an alternating electric field?

 

[Ukitake Jyuushirou]

Lasers

Not related to piezo electric effect but my lecture notes seem to neglect to state how in "stimulated emission" does the electron gets to an excited state before the incoming photons collides with it? How are stimulated emission related to spontaneous emission?

In a laser, an energy source is needed to excite the gas or crystal in the tube to produce the beam. How does the energy source create the excitation in the gas/crystal ?

What is population inversion in laser?

 

[Andrew Mason]

Not related to piezo electric effect but my lecture notes seem to neglect to state how in "stimulated emission" does the electron gets to an excited state before the incoming photons collides with it? How are stimulated emission related to spontaneous emission?

In a laser, an energy source is needed to excite the gas or crystal in the tube to produce the beam. How does the energy source create the excitation in the gas/crystal ?

What is population inversion in laser?

Without in any way intending to be unkind or to discourage your obviouis interest in the subject of physics, this is a homework board and most of the posters are not inclined to writing text-book answers. Unfortunately, these questions need textbook length answers.

AM

 

[Ukitake Jyuushirou]

Without in any way intending to be unkind or to discourage your obviouis interest in the subject of physics, this is a homework board and most of the posters are not inclined to writing text-book answers. Unfortunately, these questions need textbook length answers.

AM

its alrite, my physics exam is over. thanks anyway

 

[andrevdh]

Look on HowStuffWorks

http://science.howstuffworks.com/laser.htm"

for some info on lasers.

Same site on piezoelectricity:
http://home.howstuffworks.com/question383.htm"