x Turn on thread page Beta
 You are Here: Home >< Physics

# Ultrasound - medical physics watch

1. My model answer for how transducers emit and receive frequencies ;

A varying voltage is applied to a piezoelectric crystal which makes it contract and relax at the applied frequency.
Ultrasound is produced.
When a reflected ultrasound wave strikes the crystal, a varying stress results in a voltage which varies the frequency of ultrasound.

The bit in bold is where I'm unsure. Is that how a transducer receive ultrasound frequencies? Personally, it doesn't really feel like I've explained anything. :| like it explains half, but it's missing something crucial.

Could someone help me improve it?
2. I'd just change it slightly:

A varying voltage is applied to a piezoelectric crystal which makes it contract and relax at the applied frequency.
Ultrasound waves are produced (which are the same frequency of the contractions).
Ultrasound waves travel through various tissues or materials. Some of the waves are reflected at the boundaries where different materials meet. The reflected waves travel back towards the crystal, hit it, and cause it to vibrate at a new frequency. This vibration causes a varying stress which in turn induces a voltage. The time the wave took to be reflected, the amplitude and the frequency are calculated, so distances to each different material can be calculated and an image formed.

Hope this helps. It's a bit longer but could be shortened, but describes the process a bit more completely.
3. (Original post by pianofluteftw)
I'd just change it slightly:

A varying voltage is applied to a piezoelectric crystal which makes it contract and relax at the applied frequency.
Ultrasound waves are produced (which are the same frequency of the contractions).
Ultrasound waves travel through various tissues or materials. Some of the waves are reflected at the boundaries where different materials meet. The reflected waves travel back towards the crystal, hit it, and cause it to vibrate at a new frequency. This vibration causes a varying stress which in turn induces a voltage. The time the wave took to be reflected, the amplitude and the frequency are calculated, so distances to each different material can be calculated and an image formed.

Hope this helps. It's a bit longer but could be shortened, but describes the process a bit more completely.
That's actually perfect, thanks!

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: May 15, 2013
Today on TSR

### I've studied the wrong subject

...Should I go back to school?

### Should I complain about my supervisor?

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE