Question 19M.3.HL.TZ1.15
| Date | May 2019 | Marks available | [Maximum mark: 6] | Reference code | 19M.3.HL.TZ1.15 |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Outline, Suggest | Question number | 15 | Adapted from | N/A |
Outline how ultrasound, in a medical context, is produced.
[2]
mention of AC voltage OR to piezo-electric crystal ✔
crystal vibrates «at its resonant frequency» ✔
Production of ultrasound. This is not well known by many candidates. Quite a high number wrote generally correct information or statements about ultrasound, but these were not related or well considered responses directed to the question, for example, “use of gel in ultrasound medical applications”.
Suggest the advantage in medical diagnosis of using ultrasound of frequency 1 MHz rather than 0.1 MHz.
[2]
1 MHz waves have shorter wavelength than 0.1 MHz ✔
can probe smaller size areas of organs/have higher resolution ✔
In (b) the higher resolution was mentioned by only the best candidates. Some candidates mentioned the notion of “smaller penetration at higher frequencies” – correct, though again not well related to what the question was asking.
Ultrasound can be used to measure the dimensions of a blood vessel. Suggest why a B scan is preferable to an A scan for this application.
[2]
a B scan is a computer generated combination of a large number of A scans ✔
allowing a measurement in different directions/two dimensional image ✔
Part c) was also difficult to answer for most of the candidates.