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Question 19M.3.HL.TZ2.17aii

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.HL.TZ2.17aii
Level HL Paper 3 Time zone TZ2
Command term Suggest Question number aii Adapted from N/A
aii.
[Maximum mark: 2]
19M.3.HL.TZ2.17aii

An ultrasound A-scan is performed on a patient.

(aii)

Suggest why ultrasound gel is necessary during an ultrasound examination.

[2]

Markscheme

gel has similar Z to skin

OR

gel prevents acoustic mismatch ✔

without gel much ultrasound is reflected at skin

OR

gel increases ultrasound transmission ✔

OWTTE

Examiners report

Most candidates mentioned that the gel improves the transmission of ultrasound. On quite a few occasions candidates seemed to confuse acoustic impedance and refractive index.

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